Pre-Algebra Examples



\begin{array}{r} r = & 3 cm \end{array}

$\begin{array}{r} r = & 3 cm \end{array}$

Step 1

The circumference of a circle is equal to Pi

π

$π$ times the diameter

d

$d$ .

π \cdot (d i a m e t e r)

$π \cdot (d i a m e t e r)$

Step 2

Since the diameter

d

$d$ is equal to

2

$2$ times the radius

r

$r$ , the formula for circumference using radius is

2 π r

$2 π r$ .

2 π \cdot (r a d i u s)

$2 π \cdot (r a d i u s)$

Step 3

Substitute the value of the radius

r = 3

$r = 3$ into the formula for the area of a circle. Pi

π

$π$ is approximately equal to

3.14

$3.14$ .

2 \cdot π \cdot 3

$2 \cdot π \cdot 3$

Step 4

Multiply

3

$3$ by

2

$2$ .

6 π cm

$6 π cm$