Cheat Sheet with ACT Math Formulas

Cheat Sheet with ACT Math Formulas

You may print this ACT math Formulas Cheat Sheet for your own reference.

However, this sheet may not be electronically reproduced or posted on online forums or document-sharing platforms.

Cheat Sheet -ACT math Formulas 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-ACT math Formulas 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-ACT math Formulas 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.