Exercise 5 Page 650

Let's consider the given circle.

We want to find the circumference and area of the circle. Let's do these things one by one.

Finding the Circumference

Recall that the circumference C of a circle equals π times twice its radius r. C = 2 π r Since the diameter of the circle is 16.8 miles, the radius of the circle is ( 12* 16.8) miles or 8.4 miles. Let's calculate the circumference using this information. Remember, we are asked to use 3.14 as an estimation of π.

We found that C ≈ 52.8, which means that the circumference of the circle is about 52.8 miles.

Finding the Area

Recall that the area A of a circle equals the product of π and the square of its radius r. A = π r^2 Let's calculate the area of the given circle. Again, we will substitute 8.4 for r and 3.14 for π.

The area of the circle is about 221.6 square miles.