## Basic College Mathematics (10th Edition)

Diameter of the Circle: 20 mi Area of the Circle: 314 mi$^{2}$
a) We know the circumference of the circle. We simple divide the circumference by $\pi$ to get the diameter. Circumference of a Circle: $C$ = $\pi$$d Therefore: 62.8 mi = 3.14d d = 20 mi b) Area of a Circle: A = \pi$$d$$^{2}$ / 4 $A$ = (3.14)(20 mi)$^{2}$ / 4 $A$ = 314 mi$^{2}$