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Assam ASSEB HS Skill Engineering Drawing study materials
Assam ASSEB HS Skill Engineering Drawing study resources

Assam ASSEB HS Skill Engineering Drawing practice questions

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Question 1Drawing Instruments, Materials and Standard Practices

In engineering drawing practice, which pencil grade is conventionally used for drawing the final visible outlines of an object?

  1. 6B or softer
  2. 2H or harder
  3. HB or B Correct answer.
  4. 9H

Explanation

Visible outlines must be dark and firm, so a medium-soft grade such as HB or B is chosen; it holds a sharp point and produces strong, opaque lines. Harder grades are reserved for construction and guide lines that must remain faint. Very soft grades smudge and blunt quickly, so they are unsuitable for precise outlines.

Question 2Drawing Instruments, Materials and Standard Practices

Which drawing sheet size is the standard A-series size immediately larger than A4?

  1. A3 Correct answer.
  2. A1
  3. A5
  4. A2

Explanation

The ISO A series halves each successive sheet area, so each size is half the previous one. A3 is therefore exactly twice the area of A4 and is the next size larger. A5 is smaller than A4, and A2 and A1 are several steps larger.

Question 3Drawing Instruments, Materials and Standard Practices

A drawing is prepared to a scale of 1:50. What does this indicate about the drawn object?

  1. The drawing is the same size as the real object.
  2. The drawing is fifty times larger than the real object.
  3. The drawing uses fifty different units of measurement.
  4. The drawing is one-fiftieth the size of the real object. Correct answer.

Explanation

In a scale ratio, the first number represents the drawing and the second the real object. A ratio of 1:50 therefore means one unit on paper corresponds to fifty units on the object, so the drawing is a reduced representation. This is a typical reducing scale for buildings and large components.

Question 4Drawing Instruments, Materials and Standard Practices

Which line type is used to show the hidden internal features of a machine part?

  1. Chain thin line
  2. Short dashes of medium thickness Correct answer.
  3. Continuous thin line
  4. Continuous thick line

Explanation

Hidden edges and outlines are shown by a series of short dashes of medium thickness, evenly spaced. Continuous thick lines are reserved for visible outlines, and continuous thin lines for dimension and projection lines. Chain thin lines mark centre lines and cutting planes.

Question 5Drawing Instruments, Materials and Standard Practices

What is the primary purpose of a T-square in a drawing office?

  1. To erase pencil marks without damaging the sheet
  2. To sharpen pencils to a fine conical point
  3. To guide horizontal lines and support set squares for drawing parallel and perpendicular lines Correct answer.
  4. To measure angles directly in degrees

Explanation

The stock of a T-square rests against the edge of the drawing board, and its blade provides a horizontal reference edge. Sliding the stock along the board lets you draw parallel horizontal lines, and set squares placed against the blade give vertical and inclined lines. It is a guiding instrument, not a measuring or erasing tool.

Question 6Drawing Instruments, Materials and Standard Practices

A drawing must show a component measuring 240 mm at a scale of 1:4. What length is drawn on the sheet?

  1. 960 mm
  2. 120 mm
  3. 24 mm
  4. 60 mm Correct answer.

Explanation

For a reducing scale of 1:4, the drawing length equals the real length divided by four. Dividing 240 mm by 4 gives 60 mm on paper. Multiplying instead would apply an enlarging scale, and dividing by ten or two uses the wrong ratio.

Question 7Drawing Instruments, Materials and Standard Practices

Which instrument is most suitable for drawing a circle of 3 mm radius accurately?

  1. Bow compass Correct answer.
  2. Large bow compass
  3. French curve
  4. Divider

Explanation

A bow compass is a small compass with a spring and adjusting screw, designed for drawing small circles and arcs accurately. A large compass becomes unstable below about 10 mm radius. Dividers transfer distances rather than draw circles, and French curves guide irregular curves only.

Question 8Drawing Instruments, Materials and Standard Practices

A line on a drawing is drawn 45 mm long to represent an actual length of 1.8 m. Which scale has been used?

  1. 4:1
  2. 1:4
  3. 1:400
  4. 1:40 Correct answer.

Explanation

Both lengths must be in the same unit: 1.8 m equals 1800 mm. The ratio of drawing to object is 45:1800, which simplifies by dividing by 45 to 1:40. This is a reducing scale, consistent with the drawing being much smaller than the object.

Question 9Drawing Instruments, Materials and Standard Practices

In a drawing, a point where the centre line and an edge line meet should be handled in which way?

  1. The centre line is extended beyond the outline by a short distance. Correct answer.
  2. The centre line is drawn as a thick continuous line at the meeting point.
  3. The centre line is replaced by a hidden line near the edge.
  4. The centre line stops exactly at the outline with no extension.

Explanation

Centre lines are drawn as chain thin lines and should extend a short distance beyond the outline they locate, so the centre of the feature is clearly indicated. This small overrun is a standard convention and distinguishes centre lines from visible edges. Stopping exactly at the outline obscures the centre reference.

Question 10Drawing Instruments, Materials and Standard Practices

Which set square combination is needed to construct an angle of 75 degrees?

  1. 45-degree and 30-60 set squares used together Correct answer.
  2. 45-degree set square alone
  3. 30-60 set square alone
  4. 60-degree set square used twice

Explanation

A 75-degree angle is obtained by combining 45 degrees from the 45-degree set square with 30 degrees from the 30-60 set square. Neither set square alone contains 75 degrees, and repeating the 60-degree angle cannot produce 75 degrees. Combining the two instruments is the standard construction.

Question 11Drawing Instruments, Materials and Standard Practices

A drawing sheet is to be folded so that it fits a standard file folder. Which practice keeps the title block visible on the folded drawing?

  1. Roll the sheet into a cylinder before filing
  2. Trim the sheet to remove the title block
  3. Fold the sheet with the drawing face inward and the title block hidden
  4. Fold so the title block ends up on the outside of the final fold Correct answer.

Explanation

Standard drawing office practice folds sheets so that the title block remains visible on the outside of the folded packet. This allows the drawing to be identified without unfolding it. Folding the title block inward or removing it defeats the purpose of the title block.

Question 12Drawing Instruments, Materials and Standard Practices

Which statement correctly describes the difference between a scale and a representative fraction (RF)?

  1. An RF is used only for maps, while a scale is used only for machine parts.
  2. A scale is written with units, while an RF is a unitless ratio. Correct answer.
  3. A scale is always enlarging, while an RF is always reducing.
  4. A scale and an RF are unrelated concepts in drawing practice.

Explanation

A representative fraction expresses the ratio of drawing length to object length as a pure fraction, such as 1/50, with no units attached. A scale may be stated with units, for example 1 cm equals 50 cm, or drawn graphically. Both describe the same proportional relationship.

Question 13Drawing Instruments, Materials and Standard Practices

A drawing is to be made at a scale of 1:25 on an A3 sheet. What is the largest real object dimension that can be represented along the 420 mm length of the sheet, ignoring margins?

  1. 1.05 m
  2. 2.5 m
  3. 10.5 m Correct answer.
  4. 16.8 m

Explanation

At 1:25, each millimetre on paper represents 25 mm on the object. The 420 mm sheet length therefore represents 420 times 25 mm, which equals 10500 mm, or 10.5 m. Dividing instead of multiplying would give a much smaller value and misapply the scale.

Question 14Drawing Instruments, Materials and Standard Practices

Why is a hard pencil grade such as 4H preferred for drawing construction and projection lines that will later be erased?

  1. It is softer than HB and therefore easier to erase.
  2. It is the only grade that can be sharpened to a point.
  3. It leaves a light line that does not smudge and erases cleanly without indenting the sheet. Correct answer.
  4. It produces dark, permanent lines that resist erasing.

Explanation

Hard grades deposit less graphite, giving faint lines that guide the drawing without competing with the final outlines. The thin, light deposit erases cleanly and does not smudge under the hand. Light pressure also avoids grooving the paper surface, which would show through later work.

Question 15Drawing Instruments, Materials and Standard Practices

A draftsman draws a component at 1:2 and then photocopies the sheet at 200 percent enlargement. What is the effective scale of the resulting copy relative to the real object?

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

Explanation

The original drawing is half the real size. Enlarging the copy to 200 percent doubles every length, so the copy is twice the original drawing size. Half of the real size doubled returns to the real size, giving an effective scale of 1:1.

Question 16Drawing Instruments, Materials and Standard Practices

Which material property makes a drafting film preferable to ordinary drawing paper for a drawing that will be reproduced many times?

  1. Its high absorbency of water-based ink
  2. Its low cost and disposability
  3. Its dimensional stability and tough surface that withstand repeated erasure Correct answer.
  4. Its ability to dissolve graphite completely

Explanation

Drafting film is a stable polyester base with a matte surface that accepts pencil and ink while resisting wear from repeated erasing. Its dimensional stability keeps dimensions accurate through handling and reproduction. Ordinary paper fibres roughen and shrink with repeated erasure.

Question 17Lettering, Dimensioning and Geometrical Construction

In engineering drawing, which lettering style is specified by IS 696 for general use on drawing sheets?

  1. Copperplate script letters
  2. Ornamental serif capitals
  3. Single-stroke vertical or inclined Gothic letters Correct answer.
  4. Freehand cursive lowercase only

Explanation

IS 696 recommends single-stroke Gothic lettering, either vertical or inclined at 75 degrees, because it is quick to draw and highly legible. Ornamental and cursive styles are avoided since they slow the draughtsman and reduce clarity at small sizes.

Question 18Lettering, Dimensioning and Geometrical Construction

The height of capital letters in a drawing title block is generally kept within which range as per standard practice?

  1. 25 mm to 40 mm
  2. 12 mm to 20 mm
  3. 1 mm to 2 mm
  4. 3 mm to 7 mm Correct answer.

Explanation

Standard practice keeps title-block capital letters between about 3 mm and 7 mm so they remain readable on a full sheet without dominating the layout. Very small sizes fail on reproduction and very large sizes waste drawing space.

Question 19Lettering, Dimensioning and Geometrical Construction

For a drawing where the main lettering height is h, the recommended height of lowercase letters is:

  1. About 1.4 h
  2. About 0.7 h Correct answer.
  3. Equal to h
  4. About 0.3 h

Explanation

The standard proportion sets lowercase body height at roughly 0.7 of the capital height h, with ascenders and descenders extending beyond it. This keeps the x-height visually balanced against capital letters in mixed text.

Question 20Lettering, Dimensioning and Geometrical Construction

The ratio of height to width of a single-stroke capital letter in the standard narrow proportion is closest to:

  1. 1:2
  2. 3:2
  3. 1:1
  4. 6:5 Correct answer.

Explanation

Standard lettering proportions give a height-to-width ratio of about 6:5 for normal letters, with wider letters such as M and W excepted. This proportion keeps the lettering compact yet legible when many notes must fit on a sheet.

Question 21Lettering, Dimensioning and Geometrical Construction

Inclined lettering as recommended by IS 696 is drawn with the stems inclined at what angle to the horizontal?

  1. 75 degrees Correct answer.
  2. 45 degrees
  3. 60 degrees
  4. 90 degrees

Explanation

Inclined single-stroke lettering uses stems sloped at 75 degrees to the horizontal, which is the standard italic angle for drawing text. Vertical lettering uses 90 degrees and is the alternative permitted style.

Question 22Lettering, Dimensioning and Geometrical Construction

The guide lines used to keep lettering uniform in height are drawn as:

  1. Chain thick lines
  2. Dashed centre lines
  3. Light thin lines that may be left or erased Correct answer.
  4. Heavy continuous lines

Explanation

Guide lines are drawn lightly in HB pencil so that they control letter height without competing visually with the finished text, and they may be erased after lettering. Heavy lines would spoil the appearance of the finished drawing.

Question 23Lettering, Dimensioning and Geometrical Construction

Which pencil grade is most suitable for drawing the light guide lines and construction lines in lettering work?

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

Explanation

Hard grades such as H or 2H give faint, clean guide and construction lines that do not smudge and are easily erased. Soft grades deposit heavy graphite that dirties the sheet and is hard to remove cleanly.

Question 24Lettering, Dimensioning and Geometrical Construction

A dimension value of 45 mm is to be placed on a drawing. According to standard dimensioning practice the figure should be written:

  1. As 0.045 m beside every dimension line
  2. As 45 with the unit stated once in a general note Correct answer.
  3. As 45 mm with the unit repeated at every dimension
  4. As 45.0 mm to two decimal places

Explanation

When all dimensions on a drawing are in millimetres, the unit is declared once in a general note and the figures are written plain, for example 45. Repeating the unit at every dimension clutters the drawing and is not standard.

Question 25Lettering, Dimensioning and Geometrical Construction

In aligned dimensioning, the dimension figures are placed:

  1. At right angles to the dimension line
  2. Always horizontal, read from the bottom of the sheet
  3. Parallel to the dimension line and readable from the bottom or right Correct answer.
  4. At 45 degrees to the dimension line

Explanation

Aligned dimensioning writes each figure parallel to its dimension line so it reads along that line, oriented to be read from the bottom or from the right-hand edge. This is the preferred method under IS 11669 for general engineering drawings.

Question 26Lettering, Dimensioning and Geometrical Construction

A leader line used to connect a note or dimension to a feature should normally be drawn:

  1. Curved, following the contour of the part
  2. At 90 degrees to the outline
  3. At about 30 to 60 degrees, ending with an arrowhead or dot on the feature Correct answer.
  4. Parallel to the nearest visible edge

Explanation

Leader lines run at a convenient angle, typically 30 to 60 degrees, from the note to the feature and terminate with an arrowhead touching the line or a dot inside the area. They should be straight and never curved or parallel to the outline.

Question 27Lettering, Dimensioning and Geometrical Construction

The dimension line in a linear dimension should be drawn:

  1. As a thin continuous line with a small gap from the extension lines Correct answer.
  2. As a dashed line between the extension lines
  3. As a thick continuous line touching the object outline
  4. As a chain line through the centre of the feature

Explanation

Dimension lines are thin continuous lines terminated by arrowheads at the extension lines, with a small gap where they meet those lines. They must be lighter than the object outline so the shape of the part stays dominant.

Question 28Lettering, Dimensioning and Geometrical Construction

A dimension of 30 mm is drawn with a 5 mm arrowhead at each end. If the space between extension lines is only 8 mm, the recommended practice is to:

  1. Shift the dimension to another view
  2. Omit the dimension entirely
  3. Place the arrowheads outside and extend the dimension line beyond the extension lines Correct answer.
  4. Reduce the arrowhead to a dot and keep it inside

Explanation

When the space between extension lines is too small for arrowheads and figures, the arrowheads are placed outside the extension lines with the dimension line extended, and the figure is written between the extended lines. This keeps the dimension readable without crowding.

Question 29Lettering, Dimensioning and Geometrical Construction

In a drawing, the symbol R placed before a figure such as R25 indicates:

  1. A diameter of 25 mm
  2. A reference dimension of 25 mm
  3. A chamfer of 25 mm
  4. A radius of 25 mm Correct answer.

Explanation

The prefix R denotes radius, so R25 means an arc or circle portion of radius 25 mm drawn from a stated centre. Diameter uses the symbol with a slash through a circle, and reference dimensions are shown in brackets.

Question 30Lettering, Dimensioning and Geometrical Construction

A hole is dimensioned as '4 holes, diameter symbol 10, through'. This note means:

  1. Four holes of 10 mm depth each
  2. Four holes of 10 mm radius through the part
  3. Four holes each of 10 mm diameter drilled completely through the part Correct answer.
  4. A single hole of 4 mm diameter and 10 mm depth

Explanation

The count precedes the diameter symbol and the word 'through' states that the holes pass entirely through the material. Each of the four holes therefore has a 10 mm diameter and full depth.

Question 31Lettering, Dimensioning and Geometrical Construction

Which statement about extension lines is correct?

  1. They start with a small gap from the outline and extend slightly beyond the dimension line Correct answer.
  2. They are drawn as thick dashed lines
  3. They replace the dimension line when space is short
  4. They touch the object outline and cross the dimension line

Explanation

Extension lines begin a small gap away from the object outline and run a little past the dimension line, so they never merge with the visible edge. They are thin continuous lines drawn perpendicular to the dimension line.

Question 32Lettering, Dimensioning and Geometrical Construction

To bisect a straight line AB of length 80 mm using a compass, the radius used from A and from B must be:

  1. Equal to 80 mm
  2. Greater than 40 mm Correct answer.
  3. Exactly 40 mm
  4. Less than 40 mm

Explanation

The arcs from A and B must intersect, which requires each radius to exceed half of AB, that is more than 40 mm. Any radius greater than half the line works, and the intersection points define the perpendicular bisector.

Question 33Lettering, Dimensioning and Geometrical Construction

A perpendicular to a line at a point on it is to be erected using the 3-4-5 method. If the two legs measured along the two directions are 3 units and 4 units, the hypotenuse must be:

  1. 25 units
  2. 12 units
  3. 7 units
  4. 5 units Correct answer.

Explanation

The 3-4-5 triangle is right-angled because 3 squared plus 4 squared equals 5 squared, so a hypotenuse of 5 units confirms the 90-degree angle. Setting the two legs in the ratio 3:4 and adjusting until the hypotenuse reads 5 gives an accurate perpendicular.

Question 34Lettering, Dimensioning and Geometrical Construction

To draw a perpendicular to a line from a point outside it, the first step with a compass is to:

  1. Draw a 60-degree angle at one end
  2. Draw a circle of radius equal to the line length
  3. Bisect the given line first
  4. Draw an arc from the external point cutting the given line at two points Correct answer.

Explanation

With the compass centred on the external point, an arc is swung to cut the given line at two points. The perpendicular bisector of that chord then passes through the external point and is the required perpendicular.

Question 35Lettering, Dimensioning and Geometrical Construction

A regular hexagon is to be constructed on a circle of 40 mm diameter. The side of the hexagon equals:

  1. 10 mm
  2. 20 mm Correct answer.
  3. 40 mm
  4. 34.6 mm

Explanation

For a regular hexagon inscribed in a circle, the side length equals the radius of the circumscribing circle. With a 40 mm diameter the radius is 20 mm, so each side of the hexagon is 20 mm.

Question 36Lettering, Dimensioning and Geometrical Construction

The exterior angle of a regular polygon with n sides is calculated as:

  1. 360 degrees divided by n Correct answer.
  2. (n minus 2) times 180 degrees
  3. n times 90 degrees
  4. 180 degrees divided by n

Explanation

The exterior angles of any convex polygon sum to 360 degrees, so each exterior angle of a regular polygon is 360 divided by n. The interior angle is then 180 minus that value.

Question 37Lettering, Dimensioning and Geometrical Construction

A regular pentagon is to be inscribed in a circle. Each interior angle of the pentagon measures:

  1. 72 degrees
  2. 120 degrees
  3. 90 degrees
  4. 108 degrees Correct answer.

Explanation

The interior angle of a regular n-gon is (n minus 2) times 180 divided by n, which for n equal to 5 gives 108 degrees. The 72-degree value is the central angle subtended by each side, not the interior angle.

Question 38Lettering, Dimensioning and Geometrical Construction

An ellipse is to be drawn by the concentric-circle method using major axis 80 mm and minor axis 50 mm. The two construction circles have diameters:

  1. 80 mm and 50 mm Correct answer.
  2. 65 mm and 65 mm
  3. 40 mm and 25 mm
  4. 80 mm and 25 mm

Explanation

The concentric-circle method draws one circle on the major axis as diameter and one on the minor axis as diameter, both centred on the ellipse centre. Hence the circles are 80 mm and 50 mm across respectively.

Question 39Lettering, Dimensioning and Geometrical Construction

In the rectangle method of constructing an ellipse, the rectangle used has sides equal to:

  1. The major and minor axes Correct answer.
  2. Half the major and half the minor axes
  3. The major axis and the semi-minor axis
  4. Twice the major and twice the minor axes

Explanation

The rectangle method encloses the ellipse in a rectangle whose length is the major axis and whose width is the minor axis. The axes divide this rectangle into four quadrants that are subdivided to plot points on the curve.

Question 40Lettering, Dimensioning and Geometrical Construction

A cycloid is generated by a point on a circle of 30 mm diameter rolling without slipping along a straight line. The length of the base line of the cycloid equals:

  1. 60 mm
  2. 47.1 mm
  3. 94.2 mm Correct answer.
  4. 30 mm

Explanation

One complete arch of a cycloid has a base equal to the circumference of the rolling circle, that is pi times the diameter. With a 30 mm diameter the circumference is about 94.2 mm.

Question 41Orthographic Projection of Points, Lines and Planes

In first-angle orthographic projection, where is the top view of an object placed relative to its front view?

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

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 and appears below the front view on the sheet. This is the standard convention used in Indian engineering drawing practice under SP:46.

Question 42Orthographic Projection of Points, Lines and Planes

A point lies in the second quadrant. What are the positions of its front view and top view with respect to the XY reference line?

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

Explanation

The second quadrant is bounded by the vertical plane behind the observer and the horizontal plane above it, so the point is above the horizontal plane and behind the vertical plane. Its front view therefore lies above XY and its top view also lies above XY, since the top view of a point behind the vertical plane falls above the reference line.

Question 43Orthographic Projection of Points, Lines and Planes

The projections of a point on the two reference planes coincide with each other. Where is the point located?

  1. On the XY reference line Correct answer.
  2. On the horizontal plane only
  3. At a distance from both planes
  4. On the vertical plane only

Explanation

When a point lies exactly on the intersection of the horizontal and vertical planes, its perpendicular distances from both planes are zero. Both its front view and its top view then fall on the same point of the reference line XY, so the two projections coincide.

Question 44Orthographic Projection of Points, Lines and Planes

A line is parallel to both the horizontal plane and the vertical plane. Which statement about its projections is correct?

  1. The top view is true length but the front view is a point
  2. Both views are foreshortened and inclined to XY
  3. The front view is true length but the top view is a point
  4. Both views are true length and parallel to XY Correct answer.

Explanation

A line parallel to a plane projects on that plane in true length, and a line parallel to a plane never meets it, so its projection cannot show inclination to the trace of that plane. Being parallel to both reference planes, the line gives true-length front and top views, each parallel to XY.

Question 45Orthographic Projection of Points, Lines and Planes

A straight line AB has its top view of length 60 mm parallel to XY and its front view appearing as a single point. What is the true inclination of AB?

  1. 30 degrees to the vertical plane
  2. 45 degrees to the vertical plane
  3. 0 degrees to the horizontal plane
  4. 90 degrees to the horizontal plane Correct answer.

Explanation

When the front view of a line collapses to a point, the line is perpendicular to the vertical plane, that is, it is a vertical line. A vertical line makes 90 degrees with the horizontal plane while remaining parallel to the vertical plane.

Question 46Orthographic Projection of Points, Lines and Planes

A line AB, 70 mm long, is inclined at 30 degrees to the horizontal plane and parallel to the vertical plane. What is the length of its front view?

  1. 60.6 mm Correct answer.
  2. 70 mm
  3. 40.4 mm
  4. 35 mm

Explanation

Because the line is parallel to the vertical plane, its front view shows the true inclination to the horizontal plane and its length equals the true length multiplied by the cosine of that inclination. Thus 70 cos 30 degrees equals 70 times 0.866, about 60.6 mm.

Question 47Orthographic Projection of Points, Lines and Planes

While drawing the projections of a line inclined to both reference planes, why is the locus method applied first with the line assumed parallel to one plane?

  1. To avoid drawing the XY line
  2. To convert the line into a point view
  3. To obtain the true length and true inclinations directly from the auxiliary view Correct answer.
  4. To fix the distance of the line from the reference planes

Explanation

The locus method begins by placing the line parallel to one reference plane so that one view gives the true length and the true inclination with the other plane. The apparent inclinations in the final inclined position are then obtained from the locus of the end point, which is why the auxiliary step is essential.

Question 48Orthographic Projection of Points, Lines and Planes

A plane surface is perpendicular to the vertical plane and inclined to the horizontal plane. What shape does its front view take?

  1. A point
  2. A straight line parallel to XY
  3. A foreshortened shape of the true figure
  4. A straight line inclined to XY Correct answer.

Explanation

A plane perpendicular to the vertical plane projects on that plane as a straight line, and the line shows the true inclination of the surface to the horizontal plane. Since the surface is inclined to the horizontal plane, this edge view is inclined to XY rather than parallel to it.

Question 49Orthographic Projection of Points, Lines and Planes

A square lamina of side 50 mm rests on the horizontal plane on one edge, with its surface inclined at 45 degrees to the horizontal plane. What is the true shape shown in the top view before the final inclination is applied?

  1. A straight line 50 mm long
  2. A rhombus with 45 degree angles
  3. A rectangle 50 mm by 35.4 mm Correct answer.
  4. A square of 50 mm side

Explanation

With the lamina resting on an edge and tilted about that edge, the top view is the plan of the tilted surface, which is foreshortened in the direction of tilt. The edge on the horizontal plane stays 50 mm, while the other dimension becomes 50 cos 45 degrees, about 35.4 mm, giving a rectangle.

Question 50Orthographic Projection of Points, Lines and Planes

In the projections of a plane surface, what does the auxiliary inclined line method help to determine?

  1. The distance between the two reference planes
  2. The quadrant containing the surface
  3. The point view of an edge of the surface
  4. The true shape of the surface when it is inclined to both reference planes Correct answer.

Explanation

When a surface is inclined to both reference planes, neither initial view shows the true shape. By taking an auxiliary view perpendicular to the edge view of the surface, the true shape and the true inclinations can be found, which is the purpose of the auxiliary line construction.