Pre-Algebra Examples

 $\begin{array}{r} r = & \frac{1}{8} \end{array}$

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 $r = \frac{1}{8}$ into the formula for the area of a circle. Pi $π$ is approximately equal to $3.14$ .

$2 \cdot π \cdot \frac{1}{8}$

Step 4

Cancel the common factor of $2$ .

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Step 4.1

Factor $2$ out of $2 \cdot π$ .

$2 (π) \cdot \frac{1}{8}$

Step 4.2

Factor $2$ out of $8$ .

$2 (π) \cdot \frac{1}{2 (4)}$

Step 4.3

Cancel the common factor.

$2 π \cdot \frac{1}{2 \cdot 4}$

Step 4.4

Rewrite the expression.

$π \cdot \frac{1}{4}$

Step 5

Combine $π$ and $\frac{1}{4}$ .

$\frac{π}{4}$

Step 6

The result can be shown in multiple forms.

Exact Form:

$\frac{π}{4}$

Decimal Form:

$0.78539816 \dots$