Formula Cheat Sheet: GED Math

Area

Square: A = side²

Rectangle: A = length × width

Parallelogram: A = base × height

Triangle: A = × base × height

Trapezoid: A = (base₁ + base₂) × height

Circle: A = π × radius²; π is approximately equal to 3.14.

Circumference

Circle: C = π × diameter; π is approximately equal to 3.14.

Distance between Points on a Coordinate Plane

Distance between points: ; (x₁,y₁) and (x₂,y₂) are two points on the line.

Distance Formula

Distance = rate × time

Measures of Central Tendency

Mean: (x₁ + x₂ +… + x_n – x₁) ÷ n, where x's are values for which a mean is desired and n is the total number of values for x

Median: the middle value of an odd number of ordered scores, and halfway between the two middle values of an even number of ordered scores

Perimeter

Square: P = 4 × side

Rectangle: P = 2 × length + 2 × width

Triangle: P = side₁ + side₂ + side₃

Pythagorean Theorem

a² + b² = c²; a and b are legs, and c is the hypotenuse of a right angle.

Simple Interest Formula

Interest = principal × rate × time

Slope of a Line on a Coordinate Plane

Slope of a line: (y² – y¹) ÷ (x² – x¹); (x¹, y¹) and (x², y²) are two points on the line.

Total Cost

Total cost = number of units × price per unit

Volume

Cube: V = edge₃

Rectangular solid: V = length × width × height

Square pyramid: V = × (base edge)² × height

Cone: V = × π × radius² × height; π is approximately equal to 3.14.

Cylinder: π × radius² × height; π is approximately equal to 3.14V = B × h (the area of the base times the height).

Rectangular solid: V = l × w × h

Cylinder: V = π × r² × h