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Maharashtra HSC Engineering Drawing (Technical Science) study materials
Maharashtra HSC Engineering Drawing (Technical Science) study resources

Maharashtra HSC Engineering Drawing (Technical Science) practice questions

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Question 1Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

In the standard layout of an A2 drawing sheet, what is the ratio of its area to that of an A0 sheet?

  1. One sixteenth
  2. One half
  3. One quarter Correct answer.
  4. One eighth

Explanation

The ISO A-series is built so that each successive size is obtained by halving the larger side, which halves the area. A0 to A1 halves once, and A1 to A2 halves again, so A2 carries one quarter of the A0 area.

Question 2Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A draughtsman must draw a line at exactly 30 degrees to the horizontal using only a 45-degree set square and a 60-degree set square. Which combination of set-square edges produces this angle?

  1. 30-degree edge of the 60-degree set square alone
  2. 60-degree edge minus 45-degree edge Correct answer.
  3. 45-degree edge alone against the T-square
  4. 60-degree edge plus 45-degree edge

Explanation

Standard set squares supply 30, 45, 60 and 90 degree edges, and compound angles are obtained by adding or subtracting these. Subtracting 45 from 60 leaves 15, and adding them gives 105, so the 30-degree angle is reached differently. The 30-degree edge exists directly on the 60-degree set square.

Question 3Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

Which pencil grade is most suitable for drawing the final visible outlines of a finished ink-free drawing sheet?

  1. 4B
  2. 6H
  3. HB Correct answer.
  4. 2B

Explanation

Visible outlines need a firm, dark but non-smudging line, and HB gives that balance for finished line work. Harder grades such as 6H are reserved for construction lines because they leave faint, easily erased marks, while soft grades smudge.

Question 4Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

According to the conventional proportion for engineering drawing lettering, the height of lowercase letters (excluding ascenders and descenders) is normally taken as what fraction of the capital height?

  1. One half
  2. Four fifths
  3. Three quarters
  4. Two thirds Correct answer.

Explanation

Standard lettering practice sets the body of lowercase letters at about two thirds of the capital letter height, giving visual balance between the two cases. Ascenders and descenders extend beyond this body height.

Question 5Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

What is the standard height of capital letters recommended for the main titles and drawing numbers on a drawing sheet?

  1. 5 mm
  2. 7 mm Correct answer.
  3. 3 mm
  4. 10 mm

Explanation

Lettering heights are graded by purpose: 3 to 5 mm suits notes and dimensions, while 7 mm is the usual height for titles and drawing numbers. Larger sizes are reserved for special emphasis.

Question 6Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

In IS 696 / SP 46 style drawing practice, the recommended ratio of the height of a letter to its width for single-stroke capital letters is approximately:

  1. 7 : 6 Correct answer.
  2. 1 : 1
  3. 3 : 2
  4. 7 : 4

Explanation

Single-stroke capitals are drawn with a height-to-width proportion of about 7 : 6, giving letters slightly taller than wide. This proportion keeps strokes evenly spaced and legible at small sizes.

Question 7Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A drawing sheet is being planned for a 1 : 20 scale drawing of a component 3 m long. Which sheet size should be selected so the drawing fits with a comfortable margin?

  1. A1
  2. A2
  3. A4
  4. A3 Correct answer.

Explanation

At 1 : 20 a 3 m object becomes 150 mm on paper, which fits the drawing area of an A3 sheet (420 mm by 297 mm) with room for dimensions and a title block. A4 is too narrow once borders and the title block are allowed for.

Question 8Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

The title block on a standard engineering drawing sheet is normally located at which position?

  1. Top right corner of the sheet
  2. Top left corner of the sheet
  3. Bottom right corner of the sheet Correct answer.
  4. Centre of the bottom edge

Explanation

The title block is placed in the bottom right corner so that it is visible when sheets are folded and filed with the title showing. This convention also keeps the main drawing area free on the left.

Question 9Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

What is the purpose of the border and the zone reference system marked around the edge of a drawing sheet?

  1. To allow quick location of features by grid references and protect the drawing area Correct answer.
  2. To decorate the sheet and indicate the scale
  3. To show the projection method used
  4. To record the number of revisions

Explanation

The border frames the usable drawing area, and the zone letters and numbers along the edges let a reader locate any feature quickly, as in a map grid. They also help when the drawing is folded or referenced in correspondence.

Question 10Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

Which instrument is used to draw a circle of radius 250 mm accurately when a standard bow compass cannot span that distance?

  1. Large radius compass or beam compass Correct answer.
  2. Bow compass
  3. French curve
  4. Divider

Explanation

A beam compass carries the needle and lead on a sliding bar, so it can be set to radii far beyond the capacity of a bow compass. It maintains rigidity over long spans, which a small compass cannot.

Question 11Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A line of length 87 mm must be divided into seven equal parts using geometrical construction. Which method is appropriate?

  1. Bisect the line repeatedly until seven parts appear
  2. Measure 87 divided by 7 with a scale and mark each part
  3. Draw an inclined line with seven equal divisions and project parallel lines Correct answer.
  4. Use a French curve to space the divisions

Explanation

The standard construction draws an auxiliary line at a convenient angle, steps off seven equal divisions with a divider, then joins the last division to the line end and draws parallels. This avoids cumulative measurement error from dividing 87 by 7.

Question 12Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

Which type of line is used to represent hidden edges and outlines in an engineering drawing?

  1. Continuous thick line
  2. Continuous thin line
  3. Chain thin line
  4. Short-dashed thin line Correct answer.

Explanation

Hidden outlines are drawn with short dashes of thin line weight so they are distinguishable from visible outlines. The dashes should meet at corners and not touch visible lines.

Question 13Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A drawing uses a chain thin line with long dashes at each end and a short dash in between. What does this line convention indicate?

  1. A dimension line with arrowheads
  2. An invisible edge behind a surface
  3. A centre line of a circular feature
  4. A cutting plane or section line Correct answer.

Explanation

The chain line with thickened ends marks the plane along which a section is taken, and the viewing direction is shown by arrows at the ends. Plain chain lines without thickened ends mark centre lines.

Question 14Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

In first-angle projection, where is the view from above (top view) placed relative to the front view?

  1. Below the front view Correct answer.
  2. Above the front view
  3. To the right of the front view
  4. To the left of the front view

Explanation

First-angle projection places the object between the observer and the plane, so the top view falls below the front view and the left-side view falls on the right. This is the reverse of third-angle arrangement.

Question 15Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A drawing shows a symbol of a truncated cone with the smaller end toward the observer's left and the larger end to the right, placed beside the title block. Which projection method does this symbol denote?

  1. Oblique projection
  2. Isometric projection
  3. First-angle projection
  4. Third-angle projection Correct answer.

Explanation

The truncated-cone symbol distinguishes the methods by the order of the circles: in third angle the small circle is drawn nearer the observer side of the symbol. First angle shows the reverse order, with the small end away from the observer.

Question 16Engineering Drawing Fundamentals: Instruments, Standards, Lettering, Layout

A draughtsman needs to draw several parallel horizontal lines spaced 10 mm apart quickly and accurately. Which combination of instruments is most suitable?

  1. Protractor and bow compass
  2. Roller scale and French curve
  3. Divider and French curve
  4. T-square guided along the drawing board edge with a set square Correct answer.

Explanation

The T-square stock rides on the board's true edge, giving a family of parallel horizontal lines, and spacing can be stepped with a scale or set square along it. This is faster and more reliable than measuring each line independently.

Question 17Geometric Constructions and Plane Geometry

In the conventional layout of an A2 drawing sheet according to IS 696, what are the trimmed dimensions of the sheet?

  1. 420 mm × 594 mm Correct answer.
  2. 594 mm × 841 mm
  3. 297 mm × 420 mm
  4. 841 mm × 1189 mm

Explanation

IS 696 specifies the A-series where each size is obtained by halving the larger side of the preceding size, so A2 measures 420 mm by 594 mm. A0 is 841 mm × 1189 mm, and each subsequent size halves the longer edge.

Question 18Geometric Constructions and Plane Geometry

A line 70 mm long is to be divided into seven equal parts using the geometric construction with a ray. Which instrument setting is essential for accuracy?

  1. The ray must be drawn at any convenient acute angle and marked with equal divisions using a divider set to one constant opening Correct answer.
  2. The ray must be drawn exactly at 45° to the given line
  3. The divisions on the ray must be spaced 10 mm apart regardless of ray length
  4. The ray must be drawn perpendicular to the given line

Explanation

The construction works because equal intercepts on a transversal produce proportional segments on the line. Any convenient acute angle is acceptable provided the divider opening is kept constant along the ray. The seventh mark is then joined to the far end of the line and parallels are drawn.

Question 19Geometric Constructions and Plane Geometry

Which pair of set squares, used together, allows construction of an angle of 75° directly by combination?

  1. 45° set square with a protractor only
  2. 30°-60° and 45° set squares Correct answer.
  3. Two 45° set squares
  4. Two 30°-60° set squares

Explanation

Angles obtainable by combining set squares come from sums and differences of 30°, 45° and 60°. Combining the 30° angle of one square with the 45° angle of the other gives 75°, so a 30°-60° square with a 45° square is required.

Question 20Geometric Constructions and Plane Geometry

What is the eccentricity of an ellipse?

  1. Greater than 1
  2. Equal to 1
  3. Less than 1 Correct answer.
  4. Equal to zero for all ellipses

Explanation

Eccentricity is the ratio of the distance of a point from the focus to its distance from the directrix. For an ellipse this ratio is constant and less than one, which is what distinguishes it from a parabola and a hyperbola.

Question 21Geometric Constructions and Plane Geometry

In the rectangle method of constructing a parabola, the rectangle has a base equal to the span and a height equal to twice the rise. How are the ordinates on the axis obtained?

  1. By bisecting the diagonals of the rectangle repeatedly
  2. By projecting horizontal lines from equal divisions of the vertical side onto the corresponding verticals of the base divisions Correct answer.
  3. By drawing tangents at equal angles from the vertex
  4. By joining the focus to equal divisions of the directrix

Explanation

The rectangle method divides the base into equal parts and the vertical side into the same number of equal parts. Horizontal lines from the side divisions intersect the verticals erected at the base divisions, and the intersections lie on the parabola. The curve is then drawn through these points with a French curve.

Question 22Geometric Constructions and Plane Geometry

A regular hexagon is to be inscribed in a circle of 60 mm diameter. What is the length of each side of the hexagon?

  1. 15 mm
  2. 60 mm
  3. 30 mm Correct answer.
  4. 45 mm

Explanation

For a regular hexagon inscribed in a circle, the side length equals the radius of the circumscribing circle. The diameter is 60 mm, so the radius and hence each side is 30 mm.

Question 23Geometric Constructions and Plane Geometry

A line AB of 80 mm is to be divided in the ratio 3:5 by geometric construction. What length is measured from A to the division point?

  1. 50 mm
  2. 48 mm
  3. 30 mm Correct answer.
  4. 24 mm

Explanation

Dividing in the ratio 3:5 means the total of 8 parts corresponds to 80 mm, so each part is 10 mm. The first segment from A contains 3 parts, giving 30 mm, and the remaining segment is 50 mm.

Question 24Geometric Constructions and Plane Geometry

In the focus-directrix method of drawing an ellipse, the distance between the focus and the directrix is 50 mm and the eccentricity is 2/3. What is the distance of the vertex from the focus?

  1. 10 mm
  2. 30 mm
  3. 20 mm Correct answer.
  4. 50 mm

Explanation

For a conic, the distance from focus to vertex equals e times the distance from vertex to directrix. Let the vertex distance from the directrix be x, then the focus distance is (2/3)x, and their sum equals 50 mm. Solving gives x = 30 mm, so the focus distance is 20 mm.

Question 25Geometric Constructions and Plane Geometry

A parabola is drawn with a base (span) of 100 mm and an axis height (rise) of 40 mm. In the rectangle method, the rectangle height is twice the rise. What is the rectangle height used?

  1. 100 mm
  2. 20 mm
  3. 40 mm
  4. 80 mm Correct answer.

Explanation

The rectangle method requires the rectangle height to be twice the rise of the parabola, since the vertex lies at the midpoint of the vertical side. Twice 40 mm gives 80 mm. The base equals the span of 100 mm.

Question 26Geometric Constructions and Plane Geometry

An involute of a circle of 40 mm diameter is to be drawn. What is the length of the string unwound in one complete turn, used to divide the circle for construction?

  1. Diameter equal to 40 mm
  2. Radius equal to 20 mm
  3. Half circumference equal to π × 20 mm
  4. Circumference equal to π × 40 mm Correct answer.

Explanation

The involute is traced by a point on a taut string unwinding from the circle, so one full turn corresponds to the circumference. The circumference equals π times the diameter, that is π × 40 mm. This length is divided into equal parts matching the circle divisions.

Question 27Geometric Constructions and Plane Geometry

A regular pentagon is constructed on a side of 40 mm using the general polygon method. Into how many equal parts is the semicircle on the side divided before locating the centre?

  1. Four equal parts
  2. Three equal parts
  3. Six equal parts
  4. Five equal parts Correct answer.

Explanation

In the general method for any regular polygon, a semicircle is drawn on the given side and divided into as many equal parts as the number of sides. For a pentagon this is five parts, and the second division point locates the centre.

Question 28Geometric Constructions and Plane Geometry

Two circles of radii 30 mm and 20 mm have their centres 70 mm apart. Which construction is used to draw a common external tangent?

  1. Draw an auxiliary circle of radius equal to half the centre distance
  2. Draw an auxiliary circle of radius equal to the difference of the radii and construct tangents from the larger centre Correct answer.
  3. Draw an auxiliary circle of radius equal to the sum of the radii and construct tangents from the larger centre
  4. Draw an auxiliary circle of radius equal to the larger radius alone

Explanation

For an external tangent, the auxiliary circle uses the difference of the radii, since the tangent is parallel to the line joining the centres. Tangents drawn from the centre of the larger circle to this auxiliary circle give the tangent directions. The sum of the radii is used for internal tangents.

Question 29Geometric Constructions and Plane Geometry

A cycloid is to be drawn for a generating circle of 50 mm diameter rolling on a straight line. How is the base line divided?

  1. Into twenty-four equal parts matching the diameter divisions
  2. Into eight equal parts matching the quadrant divisions
  3. Into twelve equal parts matching the twelve divisions of the rolling circle Correct answer.
  4. Into six equal parts matching the radius divisions

Explanation

In the standard cycloid construction the rolling circle is divided into twelve equal parts and the base line is divided into the same twelve parts. Each part of the base equals one-twelfth of the circumference, so the point traces the cycloid correctly.

Question 30Geometric Constructions and Plane Geometry

A hyperbola is drawn with a focus-directrix distance of 60 mm and eccentricity 3/2. What is the distance from the vertex to the directrix?

  1. 60 mm
  2. 36 mm
  3. 40 mm
  4. 24 mm Correct answer.

Explanation

Let the vertex distance from the directrix be x; then the focus distance is (3/2)x, and their sum is 60 mm. Solving gives (5/2)x = 60, so x = 24 mm. The focus distance is then 36 mm.

Question 31Geometric Constructions and Plane Geometry

In the construction of an Archimedean spiral with the pole at the centre, how is the radius of the generating circle treated?

  1. It is bisected repeatedly to give the spiral turns
  2. It is divided into six parts and rotated by 60° steps only
  3. It is divided into twelve equal parts and the radius is doubled at each step
  4. It is divided into twelve equal parts and the radius is rotated by equal angles to locate the spiral points Correct answer.

Explanation

The Archimedean spiral is generated by a point moving uniformly along a radius that rotates uniformly. The radius is divided into twelve equal parts and the radius is rotated in twelve equal angular steps, and the intersections of arcs with successive radii give the curve.

Question 32Geometric Constructions and Plane Geometry

A line AB of 60 mm is to be divided in the ratio 2:3:4 by the ray method. What is the length of the middle segment?

  1. 26.67 mm
  2. 13.33 mm
  3. 20 mm Correct answer.
  4. 30 mm

Explanation

The ratio 2:3:4 has nine parts in total, so each part is 60/9 = 6.67 mm. The middle segment corresponds to three parts, giving 20 mm. The other segments are 13.33 mm and 26.67 mm.

Question 33Geometric Constructions and Plane Geometry

A point moves so that the sum of its distances from two fixed points 80 mm apart is always 100 mm. Which conic is traced and what is its major axis?

  1. A parabola with latus rectum 100 mm
  2. An ellipse with major axis 100 mm Correct answer.
  3. A hyperbola with transverse axis 100 mm
  4. An ellipse with major axis 80 mm

Explanation

A constant sum of distances from two fixed foci defines an ellipse, and that constant sum equals the major axis. The distance between the foci, 80 mm, is the distance between the foci, not the major axis. Hence the major axis is 100 mm and the minor axis follows from the focus separation.

Question 34Geometric Constructions and Plane Geometry

An ellipse has a major axis of 100 mm and a minor axis of 60 mm. What is the distance between its foci?

  1. 80 mm Correct answer.
  2. 40 mm
  3. 50 mm
  4. 20 mm

Explanation

For an ellipse the focal distance c satisfies c² = a² − b², where a and b are the semi-axes. Here a = 50 mm and b = 30 mm, so c² = 2500 − 900 = 1600 and c = 40 mm. The distance between the two foci is 2c = 80 mm.

Question 35Geometric Constructions and Plane Geometry

A tangent is to be drawn to a circle of radius 25 mm from an external point 65 mm from the centre. What is the length of the tangent?

  1. 60 mm Correct answer.
  2. 25 mm
  3. 90 mm
  4. 40 mm

Explanation

The tangent, radius and line from the centre to the external point form a right triangle with the radius perpendicular to the tangent. Hence the tangent length is the square root of (65² − 25²), that is the square root of 3600, which is 60 mm.

Question 36Geometric Constructions and Plane Geometry

In the construction of a hypocycloid, the generating circle rolls inside the directing circle. If the generating circle diameter equals half the directing circle diameter, how many cusps does the curve have?

  1. One cusp
  2. Eight cusps
  3. Four cusps
  4. Two cusps Correct answer.

Explanation

The number of cusps equals the ratio of the directing circle radius to the generating circle radius. If the generating diameter is half the directing diameter, the ratio of radii is 2, so the hypocycloid has two cusps and degenerates into a straight line through the centre.

Question 37Orthographic Projections of Points, Lines, and Planes

In first-angle orthographic projection, how is the top view positioned relative to the front view?

  1. Below the front view Correct answer.
  2. Above the front view
  3. To the left of the front view
  4. To the right of the front view

Explanation

In first-angle projection the object is imagined between the observer and the plane, so the view seen from above is projected onto a plane below the object. The resulting top view is therefore drawn below the front view, and the side view is placed on the far side from the observer.

Question 38Orthographic Projections of Points, Lines, and Planes

A point lies in the horizontal plane. What is the position of its front view?

  1. Above the XY line at a distance equal to its height
  2. At the same vertical level as its top view but offset horizontally
  3. Below the XY line at a distance equal to its depth
  4. On the XY reference line Correct answer.

Explanation

The front view of a point shows its height above the horizontal plane, measured from the XY line. A point lying exactly in the horizontal plane has zero height, so its front view falls on the XY reference line itself. Its top view still shows the true distance from the vertical plane.

Question 39Orthographic Projections of Points, Lines, and Planes

A line is parallel to both the horizontal plane and the vertical plane. What does its front view show?

  1. A line parallel to XY, showing the true length Correct answer.
  2. A point
  3. A line parallel to XY, showing the foreshortened length
  4. A line inclined to XY, showing the true length

Explanation

A line parallel to both reference planes stays at constant height and constant depth, so both its views are parallel to XY. Because the line is parallel to the vertical plane, the front view shows the true length. The top view is also parallel to XY and equally true in length.

Question 40Orthographic Projections of Points, Lines, and Planes

In first-angle projection, the top view of an object is obtained by projecting rays onto which plane?

  1. The horizontal plane placed below the object Correct answer.
  2. The vertical plane placed behind the object
  3. The profile plane placed to the right of the object
  4. The auxiliary plane inclined to both reference planes

Explanation

The top view records the shape seen from above, so the rays travel downward and strike a horizontal plane. In first-angle projection this plane is located below the object, and the view is later rotated into the drawing sheet. The vertical plane behind the object receives the front view instead.

Question 41Orthographic Projections of Points, Lines, and Planes

A point is 30 mm above the horizontal plane and 20 mm in front of the vertical plane. Which pair of coordinates describes its two views?

  1. Front view 30 mm above XY, top view 30 mm below XY
  2. Front view 30 mm above XY, top view 20 mm below XY Correct answer.
  3. Front view 20 mm above XY, top view 20 mm below XY
  4. Front view 20 mm above XY, top view 30 mm below XY

Explanation

The front view is placed above XY at a distance equal to the point's height above the horizontal plane, so 30 mm. The top view is placed below XY at a distance equal to the point's distance in front of the vertical plane, so 20 mm. The two distances measure different things and must not be interchanged.

Question 42Orthographic Projections of Points, Lines, and Planes

Which statement correctly describes the projection of a plane surface parallel to the vertical plane?

  1. Both views appear as straight lines
  2. Its top view shows the true shape and size
  3. Both views show the true shape and size
  4. Its front view shows the true shape and size Correct answer.

Explanation

A plane parallel to the vertical plane is seen without distortion when viewed from the front, so the front view gives the true shape. Because it is perpendicular to the horizontal plane, its top view collapses to a straight line parallel to XY. Only one view can show the true shape in this orientation.

Question 43Orthographic Projections of Points, Lines, and Planes

What is the purpose of the XY reference line in orthographic projection of points?

  1. It shows the direction of the observer's line of sight
  2. It marks the centre line of the drawing sheet
  3. It represents the intersection of the horizontal and vertical planes Correct answer.
  4. It indicates the ground level of the object

Explanation

The horizontal and vertical planes meet along a line, and when the planes are unfolded into the drawing sheet this intersection appears as the XY line. Distances of front views are measured above or below it, and distances of top views are measured from it as well. It is a datum for both views, not a decorative centre line.

Question 44Orthographic Projections of Points, Lines, and Planes

A straight line is inclined at 30 degrees to the horizontal plane and is parallel to the vertical plane. What does its front view show?

  1. A line inclined at 30 degrees to XY with true length Correct answer.
  2. A line inclined at 30 degrees to XY with foreshortened length
  3. A point on the XY line
  4. A line parallel to XY with true length

Explanation

When a line is parallel to the vertical plane, that plane receives its true length, so the front view is not foreshortened. The inclination to the horizontal plane appears in the front view as the angle made with XY. Hence the front view is a true-length line at 30 degrees to XY.

Question 45Orthographic Projections of Points, Lines, and Planes

The top view of a line measures 40 mm and its front view measures 50 mm. The line is parallel to the vertical plane. What is its true length?

  1. 90 mm
  2. 40 mm
  3. 50 mm Correct answer.
  4. 30 mm

Explanation

For a line parallel to the vertical plane, the front view is projected on a plane parallel to the line, so it shows the true length directly. The 50 mm front view is therefore the true length. The top view is shorter because the line is inclined to the horizontal plane.

Question 46Orthographic Projections of Points, Lines, and Planes

A line AB has its top view perpendicular to XY and its front view also perpendicular to XY. What is the true orientation of the line?

  1. Parallel to the horizontal plane and inclined to the vertical plane
  2. Perpendicular to both reference planes Correct answer.
  3. Parallel to both reference planes
  4. Inclined to both reference planes

Explanation

When both views of a line are perpendicular to XY, the line is perpendicular to both reference planes. It appears as a point in the view taken along its axis and as a true-length line perpendicular to XY in the other. Such a line is vertical or perpendicular to the profile plane depending on which views are considered.

Question 47Orthographic Projections of Points, Lines, and Planes

A square lamina of 40 mm side rests on the horizontal plane on one edge, with its surface inclined at 45 degrees to the horizontal plane and perpendicular to the vertical plane. Which view shows the edge on which it rests as a true-length line?

  1. Neither view; only an auxiliary view
  2. The front view only
  3. Both the front view and the top view
  4. The top view only Correct answer.

Explanation

Because the lamina is perpendicular to the vertical plane, the top view preserves the true lengths of lines lying in the surface. The resting edge lies in the horizontal plane, so its top view is a true-length line at 40 mm. The front view is an edge view foreshortened by the inclination.

Question 48Orthographic Projections of Points, Lines, and Planes

A point is 25 mm above the horizontal plane and lies in the vertical plane. How is its top view shown?

  1. 25 mm above XY
  2. Coincident with the front view
  3. On the XY line Correct answer.
  4. 25 mm below XY

Explanation

The top view's distance below XY equals the point's distance in front of the vertical plane. A point lying in the vertical plane has zero distance from it, so its top view lies on XY. Its front view is 25 mm above XY, showing the height.

Question 49Orthographic Projections of Points, Lines, and Planes

A line 60 mm long is inclined at 30 degrees to the horizontal plane and 45 degrees to the vertical plane. Which construction gives its front view length?

  1. 60 sin 30
  2. 60 cos 45 Correct answer.
  3. 60 cos 30
  4. 60 divided by cos 45

Explanation

The front view length equals the true length multiplied by the cosine of the angle the line makes with the vertical plane. With a true length of 60 mm and an angle of 45 degrees to the vertical plane, the front view is 60 cos 45. The angle to the horizontal plane governs the top view length instead.

Question 50Orthographic Projections of Points, Lines, and Planes

In the rotating-line method for a line inclined to both reference planes, what is established first?

  1. The true length and true inclinations using an auxiliary view parallel to the line Correct answer.
  2. The point view of the line
  3. The traces of the line on both planes
  4. The apparent angles in the front and top views

Explanation

The rotating-line method begins by making the line parallel to one reference plane so that a view shows its true length. From that true-length view the true inclinations with the horizontal and vertical planes are obtained. The apparent angles in the original views are then derived and checked against the true values.