# Pre-Algebra : Perimeter

## Example Questions

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### Example Question #1 : Circumference Of A Circle

Becky's house is surrounded by a circular lake that Becky runs around each day. If Becky wants to figure out the distance she runs around the lake, what formula should Becky use?

None of the other answers

Explanation:

Becky should use the circumfrence formula to find the distance she runs of a lake.

### Example Question #261 : Geometry

What is the circumference of a circle with an area equal to ?

Explanation:

Using the area, solve for the radius:

Divide by :

Take the square root:

Plug this radius into the formula for the circumference:

### Example Question #1 : How To Find Circumference

What is the circumference of a circle with a radius equal to ?

Explanation:

The circumference can be solved using the following equation:

### Example Question #1 : Circumference Of A Circle

What is the circumference of a circle with a radius of ?

Explanation:

The circumference can be solved using the following equation:

Where  represents the radius. Therefore, when we substitute our radius in we get:

### Example Question #1 : Know And Use The Formulas For The Area And Circumference Of A Circle: Ccss.Math.Content.7.G.B.4

The perimeter of a given rectangle is equal to the circumference of a given circle. The circle has radius  inches; the width of the rectangle is  inches. What is the length of the rectangle?

inches

inches

inches

inches

inches

inches

Explanation:

The circumference of a circle with radius  inches is

inches.

The perimeter of the rectangle is therefore  inches. To find its length, substitute  and  into the equation and solve for :

inches

### Example Question #1 : Perimeter

Determine the circumference of the circle if the radius is 20.

Explanation:

Write the formula for circumference.

Substitute the radius and solve.

### Example Question #1 : Perimeter

Given the area of the circle is , what is the circumference of the circle?

Explanation:

Write the formula for the area of a circle.

Substitute the area.

Write the circumference of the circle.

### Example Question #1 : Circumference Of A Circle

Find the circumference of a circle with an area of .

Explanation:

Write the area formula in order to find the radius.

Substitute the area.

Write the circumference formula.

### Example Question #1 : Circumference Of A Circle

Determine the circumference of the circle if the radius is .

Explanation:

Write the formula for the circumference of a circle.

Substitute the radius into the formula.

### Example Question #1 : Circumference Of A Circle

Find the circumference of a circle with a radius of .