ACT Formulas

Basic Trig Formulas

100

What is the mnemonic device used to remember the basic trigonometric formulas?

SOHCAHTOA

200

What is the formula for Sine?

Opposite / Hypotenuse

300

What is the formula for Cosine?

Adjacent / Hypotenuse

400

What is the formula for Tangent?

Opposite / Adjacent

500

What is the formula for Cotangent?

Adjacent / Opposite

Formula for Area

100

The formula for the area of a trapezoid?

1/2 h(b₁+ b₂)

200

The formula for the area of a triangle?

1/2 bh

300

The formula for area of a kite?

1/2 d₁d₂

400

What is the formula for the area of a circle?

Pi r²

500

What is the formula for the area of a parallelogram?

base * height

bh

306090 / 454590

100

The formula for a Leg of a 45-45-90 triangle?

Leg = hyp / radical (2)

200

The formula for the hypotenuse of a 45-45-90 triangle?

Hypotenuse = Leg * radical(2)

300

What is the short leg formula for a 30-60-90 triangle when given the long leg?

SL = LL / radical(3)

400

What is the formula for the hypotenuse of a 30-60-90 triangle when given the short leg?

Hypotenuse = SL * 2

500

What is the Formula for the short leg of a 30-60-90 triangle when given the hypotenuse?

Short Leg = Hypotenuse / 2

Polygons

100

Formula for total degrees in any polygon?

(n-2)180

200

Formula to find a single interior angle of a regular polygon?

(n-2)180    divided by   n 

300

Formula to find a single exterior angle of a regular polygon?

360 / n

400

Formula to find the area of a polygon?

A = (aP) divide by 2

500

Formula to find the volume of a regular polygon?

V = (aP)/2 * height

Volume

100

The formula for the Volume of a Square?

V = s³

200

The formula for the volume of a rectangular prism?

V = lwh

300

The formula for the volume of a triangular prism?

V = 1/2*bhl

400

The formula for the volume of a cone?

V = 1/3*Pi*r²h

500

The formula for the Volume of a Pyramid?

V = (Bh) / 3

V = (bhl)/3