# Basic Geometry : How to find circumference

## Example Questions

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

A circle has the equation below. What is the circumference of the circle?

(x – 2)2 + (y + 3)2 = 9

Explanation:

The radius is 3. Yielding a circumference of .

### Example Question #11 : Know And Use The Formulas For The Area And Circumference Of A Circle: Ccss.Math.Content.7.G.B.4

If a circle has an area of , what is the circumference?

Explanation:

For a circle, the formula for area is  and the formula for circumference is , where  is the radius and  is the diameter.

Plug the known quantities into the area formula and solve for the radius:

Now plug this value into the circumference formula to solve:

### Example Question #13 : How To Find Circumference

Line  is the radius of the circle shown and has a length of 7.5. What is the circumference of the circle?

Explanation:

Plug in the given value for the radius to find the circumference:

### Example Question #11 : How To Find Circumference

Find the circumference of a circle with a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #12 : How To Find Circumference

Find the circumference of a circle that has a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #11 : How To Find Circumference

Find the circumference of the circle with a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #14 : How To Find Circumference

Find the circumference of a circle with a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #15 : How To Find Circumference

Find the circumference of a circle with a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #16 : How To Find Circumference

Find the circumference of a circle with a radius of .

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

### Example Question #11 : How To Find Circumference

Find the circumference of a circle with a radius of .