Algebraic Formulas for Geometric Shapes

By Mary Jane Sterling

Part of U Can: Algebra I For Dummies Cheat Sheet

Geometric shapes have algebraic formulas for determining perimeter, area, surface area, and volume. The letters in the formulas stand for length, width, side, base, height, diameter, and radius:

l: length

w: width

s: side

b: base

h: height

d: diameter

r: radius

In this list, the shape is followed by two formulas, the first formula is for the perimeter (P) or circumference (C), and the second formula is for the area (A):

Rectangle:

P = 2(l + w) = 2l + 2w

A = lw

Square:

P = 4s

A = s2

Triangle:

P = s1 + s2 + s3

A = 12bh

Trapezoid:

P = s1 + s2 + s3 + s4

A = 12h(b1 + b2)

Parallelogram:

P = 2(b + s) = 2b + 2s

A = bh

Circle:

image0.png

In this list, the shape is followed by two formulas, the first formula is for the surface area (SA), and the second formula is for the volume (V):

Rectangular prism (box):

SA = 2lw + 2lh + 2wh

V = lwh

Cylinder:

image1.png

Sphere:

image2.png