Page 674 - Basic College Mathematics with Early Integers

S E C T I O N 9.4 I AREA 651

Area is always measured in square units.

Example 1 Find the area of the triangle. PRACTICE 1
Find the area of the triangle.

8 cm
6~ in.
1 14 cm
Solution: A = bh 8 in.
2
1
#
= # 14 cm 8 cm
2
1
# #
2 7 8
= sq cm You may see 56 sq cm,
2
1 for example, written with the notation
2
= 56 square cm 56 cm . Both of these notations mean
the same quantity.
The area is 56 square centimeters.
Work Practice 1

Example 2 Find the area of the parallelogram. PRACTICE 2
Find the area of the square.
4.2 yd
1.5 mi

Solution: 3.4 mi 4.2 yd
A = bh
#
= 3.4 miles 1.5 miles
= 5.1 square miles
The area is 5.1 square miles.
Work Practice 2

When finding the area of figures, be sure all measurements are changed to the
same unit before calculations are made.

Example 3 Find the area of the figure. PRACTICE 3
Find the area of the figure.
4 ft 24 m

12 m
18 m
8 ft
5 ft
18 m
Answers
12 ft 1. 25 sq in. 2. 17.64 sq yd
Continued on next page 3. 396 sq m