Basic Math Operations - Mathematics and Statistics for the Environment - page 60

35 ft

8 ft 8 ft

35 ft

FIGURE 2.2 Perimeter of a rectangle for Example 2.40.

■ EXAMPLE 2.40
Problem: Find the perimeter of the rectangle shown in Figure 2.2.

Solution:

P = 35 ft + 8 ft + 35 ft + 8 ft = 86 ft

■ EXAMPLE 2.41
Problem: What is the perimeter of a rectangular field if its length is 100 ft and its width is 50 ft?

Solution:

P = (2 × length) + (2 × width) = (2 × 100 ft) + (2 × 50 ft) = 200 ft + 100 ft = 300 ft

■ EXAMPLE 2.42
Problem: What is the perimeter of a square with 8-in. sides?

Solution:

P = (2 × length) + (2 × width)

= (2 × 8 in.) + (2 × 8 in.) = 16 in. + 16 in. = 32 in.

The circumference is the length of the outer border of a circle. The circumference is found by
multiplying pi (π) times the diameter ( D ) (a straight line passing through the center of a circle, or
the distance across the circle; see Figure 2.3):

C = π × D (2.5)

D

FIGURE 2.3 Diameter of circle.