Basic Mathematics for College Students

APPLICATIONS

81. SEWING The pattern that is sewn on the rear
    pocket of a pair of blue jeans is shown below. If
    , how long is the stitching from
    point to point?


82. CAMPING The base of the tent pole is placed at the
    midpoint between the stake at point and the stake
    at point , and it is perpendicular to the ground, as
    shown below. Explain why.

ABD

C

ACD  BCD

B

A

O

8 cm

9.5 cm

A

B

C

D

A D

AOB  COD

84. HEIGHT OF A BUILDING A man places a mirror
    on the ground and sees the reflection of the top of a
    building, as shown below. Find the height of the
    building.


85. HEIGHT OF A TREE The tree shown below casts a
    shadow 24 feet long when a man 6 feet tall casts a
    shadow 4 feet long. Find the height of the tree.


86. WASHINGTON, D.C. The Washington Monument
    casts a shadow of 166 12 feet at the same time as a

24 ft

h

4 ft

6 ft

h

8 ft 48 ft

6 ft

766 Chapter 9 An Introduction to Geometry

83. A surveying crew needs to
    find the width of the river
    shown in the illustration
    below. Because of a
    dangerous current, they
    decide to stay on the west
    side of the river and use
    geometry to find its width.
    Their approach is to create
    two similar right triangles on
    dry land. Then they write and solve a proportion to
    find. What is the width of the river?

20 ft 25 ft

West 74 ft East

w ft

w

© iStockphoto.com/Lukaz Laska

5-foot-tall tourist casts a shadow of feet. Find the

height of the monument.

1 ft 166 ft

5 ft

(^1) –
2
(^1) –
2
h

1 12

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