Algebra Demystified 2nd Ed

Chapter 11 QuaDraTiC appliCaTionS 417

Rectangle Formulas

D

L

W

FIGURE 11-1

•   Area A = LW

•   Perimeter (the length around its sides) P = 2L + 2W

•   Diagonal DL^22 =+W^2

Triangle Formulas

a

c

c

a

bb

B

H

Right triangle

FIGURE 11-2

•   Area AB=^1 H

2

•   Perimeter P = a + b + c (for any triangle)

•   Pythagorean theorem a^2 + b^2 = c^2 (for right triangles only)

Formulas for Other Shapes

•   Volume of a right circular cylinder V = πr^2 h, where r is the cylinder’s

radius, h is the cylinder’s height.

•   Surface area of a sphere (ball) is SA = 4πr^2 , where r is the sphere’s radius.