Pre-Algebra Demystified

EXAMPLE

Find the length of the hypotenuse of a right triangle if the length of its sides

are 5 inches and 12 inches.

SOLUTION

c¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

a^2 þb^2

p

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

52 þ 122

p

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

25 þ 144

p

¼

ffiffiffiffiffiffiffiffi

169

p

¼13 inches

EXAMPLE

A person drives 33 miles due east, then makes a left turn, and drives 56 miles

north. How far is he from his starting point?

SOLUTION

The right triangle is shown in Fig. 9-24.

Then

c¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

a^2 þb^2

p

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

332 þ 562

p

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

1089 þ 3136

p

¼

ffiffiffiffiffiffiffiffiffiffi

4225

p

¼65 miles

184 CHAPTER 9 Informal Geometry

Fig. 9-24.