## Basic College Mathematics (9th Edition)

$C = 28.26$ $A = 199.7$
The formula for circumference is $2\times\pi\times(radius)$ or $\pi\times(diameter)$ 1. The diameter is 9 so we multiply $9\times\pi\approx28.26$ The formula for area is $(\pi\times radius)^{2}$ 2. $(\pi\times4.5)^{2} = 199.7$