Pre-Algebra Examples



$\begin{array}{r} r = & 8 cm \end{array}$

Step 1

The circumference of a circle is equal to Pi

$π$ times the diameter

$d$ .

$π \cdot (d i a m e t e r)$

Step 2

Since the diameter

$d$ is equal to

$2$ times the radius

$r$ , the formula for circumference using radius is

$2 π r$ .

$2 π \cdot (r a d i u s)$

Step 3

Substitute the value of the radius

$r = 8$ into the formula for the area of a circle. Pi

$π$ is approximately equal to

$3.14$ .

$2 \cdot π \cdot 8$

Step 4

Multiply

$8$ by

$2$ .

$16 π cm$