Cheat Sheet

Cheat Sheet with Formulas

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Cheat Sheet for Coordinate Geometry


Midpoint x: (x1 + x2) ÷ 2

Midpoint y: (y1 + y2) ÷ 2

x and y intercepts:

These are the points where the line on a two-dimensional graph intersects with the x and y axes.

You will see an algebraic equation which represents the line on the two-dimensional graph.

The equation will contain the variables x and y.

To calculate the x intercept, substitute 0 for y.

To calculate the y intercept, substitute 0 for x.


y = mx + b

m = slope

b = y intercept

x, y = points on the graph or in the equation

Cheat Sheet for Plane Geometry

Area of circle:

π × R2 (radius squared)

Area of square or rectangle:

length × width

Area of triangle:

(base × height) ÷ 2


Arc length is the distance on the outside of a circle.

Calculate the circumference for the part of circle for the degrees stated.


A chord is a straight line which is drawn inside a circle.

That line connects two points on the circumference of the circle.

Use the degrees stated for the given angle to calculate chord length.

Circumference of a circle:

π × diameter

diameter = radius × 2

Cone volume:

(π × radius2 × height) ÷ 3

Cylinder volume:

V = πr2h

Volume = π times the radius squared times the height

Hypotenuse length:

Length of hypotenuse = square root of the sum of the squares of the other two sides

Perimeter of squares and rectangles:

(length × 2) + (width × 2)

Cheat Sheet for Trigonometry


θ = s ÷ r

θ = radians

s = arc length

r = radius

π × 2 × radians = 360°

π × radians = 180°

π ÷ 2 × radians = 90°

π ÷ 4 × radians = 45°

π ÷ 6 × radians = 30°

Tangent, sine, and cosine:

cos2 A + sin2 A = 1

cos2 A = 1 − sin2 A

sin2 A = 1 − cos2 A

tan A = sin A ÷ cos A

You can get more math help for the ACT from our math formulas section, our free sample test, and our ACT download.