Exercise 58 Page 468

Let's find the circumference and the area of the circle separately.

The circumference

C

of a circle with radius

r

is calculated using the formula below.

C = 2 π r

From the exercise, we know that the radius of the circle is

11 inches .

By substituting

11

for

r

in the formula, we can calculate

C .

C = 2 π r

$r = 11$

C = 2 π (11)

C = 22 π

Use a calculator

C = 69.115038 \dots

Round to $1$ decimal place(s)

C \approx 69.1

The circumference of the circle is approximately

69.1 inches .

Similar to the perimeter, the area of a circle with radius

r