Pre-Algebra Chapter 9

• Extra Practice, see pages 745–747.
• Mixed Problem Solving, see page 766.
Exercises Find the distance between each pair of points. Round to the
nearest tenth, if necessary. See Example 1 on page 467.
28. J(0, 9), K(2, 7) 29. A(5, 1), B(3, 6) 30. W(8, 4), Y(3, 3)
The coordinates of the endpoints of a segment are given. Find the
coordinates of the midpoint of each segment. See Example 3 on page 468.
31. M(8, 0), N(2, 10) 32. C(5, 9), D(7, 3) 33. Q(6, 4), R(6, 8)
9-7
See pages
471–475.
Example
Similar Triangles and Indirect Measurement
Concept Summary
• If two triangles are similar, then the corresponding angles have the
same measure, and the corresponding sides are proportional.
If ABC KLM, what is the value of x?
AC
BC Write a proportion.
K M L M
x 3 2 4
x 1.5
Substitution
Find cross products and simplify.
A
B
x in.
2 in.
C
K
L
3 in.
4 in.
M
Exercises In Exercises 34 and 35, the triangles are similar. Write a proportion
to find each missing measure. Then find the value of x. See Example 1 on page 472.
34. M
35.
B
x ft
J
15 ft 9 ft
6 ft
24 m 21 m
U
A C H K
8 m x m
L N T V
9-8
See pages
477–481.
Example
Sine, Cosine, and Tangent Ratios
Concept Summary
• Trigonometric ratios compare the lengths of two sides of a right triangle.
Find cos S.
S
cos S 1 5
or 0.6
25
25
15
R
20
T
Exercises Find each sine, cosine, or tangent in RST above. Round to four
decimal places, if necessary. See Example 1 on page 478.
36. sin R 37. tan S 38. tan R
486 Chapter 9 Real Numbers and Right Triangles