SIFT cheat sheet

A match preserves the shape's outline, proportions, angle sequence, and handedness; translation and rotation are allowed, but stretching and mirroring are not.

Count line segments and endpoints; a single extra, missing, or shortened segment disqualifies an option.

Reflection reverses handedness: a mirror image is not the same drawing even when the overall outline looks similar.

Compare angles in order around the figure; a changed acute/right/obtuse sequence indicates a mismatch.

Use landmarks such as corners, intersections, and free ends; compare their relative positions rather than the whole shape at once.

Distractor types include mirrored versions, rotated versions with one altered line, scaled versions, and drawings with shifted intersections.

When drawings overlap or contain multiple parts, separate connected components and compare each component independently.

A quick first-mismatch scan eliminates options faster than repeatedly verifying every feature of every choice.

The embedded target keeps its shape and proportions; extra lines from the surrounding pattern do not change the target's identity.

Search for the target's most distinctive feature first: a sharp angle, parallel sides, symmetry, or a closed region with a specific side count.

Follow straight lines through intersections; target sides often continue across other lines and are not separated by breaks.

Count vertices and sides of a suspected region; an n-sided target must have n sides and n vertices.

Mentally subtract non-target lines; ignore decorative curves, hatching, and lines that do not form part of the target.

The target may share sides with a larger figure, so a side can belong to both the target and the surrounding shape.

Check every candidate region against all target features; a region matching only part of the target is a distractor.

Main helicopter controls: cyclic controls pitch and roll; collective controls blade pitch and lift; pedals control yaw and anti-torque thrust.

Translational lift increases as the rotor moves out of its own downwash into cleaner air, improving efficiency with forward airspeed.

Ground effect occurs near the surface, roughly within one rotor diameter, and reduces the power required to hover.

Dissymmetry of lift in forward flight is managed by blade flapping and cyclic feathering so advancing and retreating sides produce balanced lift.

Retreating blade stall is associated with high forward speed, high gross weight, high density altitude, and high load factors.

Autorotation is an engine-out descent in which upward airflow through the rotor keeps the blades turning; a flare reduces descent rate before touchdown.

Army helicopter roles include attack (AH-64), utility (UH-60), cargo (CH-47), reconnaissance, MEDEVAC, and air assault.

Vne is the never-exceed airspeed; torque, altitude, temperature, and gross weight all affect performance limits.

A pilot in command is responsible for the aircraft and crew; other crew may include copilot, crew chief, and flight medic.

Attitude indicator: blue is sky, brown is ground, and the dividing line is the horizon; the aircraft symbol is fixed while the horizon moves.

Nose-up attitude moves the horizon bar downward relative to the fixed aircraft symbol; nose-down moves the horizon bar upward.

Bank is shown by the angle between the horizon bar and the aircraft symbol; the lower wing is on the side toward which the aircraft is banked.

Heading indicator: 0/360 = north, 90 = east, 180 = south, 270 = west; the outside view must face the heading shown.

Standard-rate turn = 3 degrees per second; 90 degrees takes about 30 seconds and 180 degrees about 60 seconds.

Turn coordinator ball centered = coordinated turn; ball displaced = slip or skid.

Altimeter shows altitude; vertical speed indicator shows climb or descent rate; combine both with attitude to determine the outside view.

For each choice, check three variables: heading, bank direction/angle, and pitch attitude; one mismatch eliminates the choice.

Main idea = the central claim supported by the whole passage; details support it but do not replace it.

Supporting detail questions require locating explicit text; the correct choice restates or closely paraphrases that text.

Inference = a conclusion logically required or strongly supported by the passage, not free speculation or outside knowledge.

Vocabulary in context: substitute each answer choice into the sentence and select the meaning that preserves the passage's logic.

EXCEPT/NOT questions: eliminate choices the passage directly supports; the remaining choice is the answer.

Tone is signaled by word choice and connotation; extreme or loaded words often indicate bias or emotion.

Transition words (however, therefore, although) reveal contrast, cause, or concession and help locate the author's point.

Scope rule: an answer that is true in general but not stated or implied in the passage is incorrect.

Order of operations: parentheses, exponents, multiplication/division left to right, addition/subtraction left to right.

Percent change = (new value - old value) / old value × 100; percent of a number = percent/100 × number.

Average = sum of values / number of values; weighted average = sum(value × weight) / sum(weights).

Ratio/proportion: a/b = c/d solves by cross multiplication ad = bc.

Distance = rate × time; work rate problems add rates and use combined time = 1 / (sum of rates).

Area formulas: rectangle lw; triangle ½bh; circle πr²; circumference 2πr; volume of rectangular solid lwh.

Right triangles: a² + b² = c²; 45-45-90 sides ratio 1:1:√2; 30-60-90 ratio 1:√3:2.

Linear equation: isolate the variable by applying inverse operations to both sides; check by substitution.

Probability of independent events = product of individual probabilities; probability = favorable outcomes / total outcomes.

Lever equilibrium: effort × effort arm = load × load arm; torque = force × perpendicular distance from pivot.

Mechanical advantage = output force / input force = input distance / output distance for an ideal machine.

Pulley systems: count rope segments supporting the movable load to estimate mechanical advantage; fixed pulleys change direction only.

Gear ratio = driven teeth / driving teeth; external meshed gears rotate in opposite directions; larger driven gear turns slower with more torque.

Inclined plane MA = length / height; wedge and screw are variants of the inclined plane.

Pressure = force / area; in hydraulics, pressure is transmitted equally, so force advantage depends on piston area ratio.

Work = force × distance; power = work / time; efficiency = useful output work / input work × 100.

Friction opposes relative motion; lubrication and smooth surfaces reduce friction; static friction is usually greater than kinetic friction.

Ohm's law V = IR; series resistance adds (R_total = R1 + R2 + ...); parallel branches share voltage.