## Thinking Mathematically (6th Edition)

Circumference = $20\pi \approx 62.8$ meters Area = $100\pi \approx 314.2$ square meters
RECALL: In a circle: (1) Circumference = $C = 2\pi{r}$ (2) Area = $A = \pi{r^2}$ (3) Radius = $r = \frac{d}{2}$ where r = radius and d = diameter The given circle has a diameter of 20 meters. Since the radius is equal to half of the diameter, the radius of the circle is: $r = \frac{20}{2} = 10$ meters Solve for the circumference and the area using formulas (1) and (2), respectively, to obtain: Circumference = $2\pi(10) = 20\pi \approx 62.8$ meters Area = $\pi(10^2) = \pi(100) = 100\pi \approx 314.2$ square meters