# High School Math : How to find the circumference of a circle in pre-algebra

## Example Questions

### Example Question #1 : How To Find The Circumference Of A Circle In Pre Algebra

Find the circumference of a circle with a radius of 6 inches.

Explanation:

Use the circumference formula and plug in 6 for . Leave  in your answer to get .

### Example Question #2 : How To Find The Circumference Of A Circle In Pre Algebra

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

Explanation:

To find the circumference of a circle given the radius we must first know the equation for the circumference of a circle which is

We then plug in the number for the radius into the equation yielding

We multiply to find the value for the circumference is .

### Example Question #3 : How To Find The Circumference Of A Circle In Pre Algebra

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

Explanation:

To find the circumference of a circle given the radius we must first know the equation for the circumference of a circle which is

We then plug in the number for the radius into the equation yielding

We multiply to find the value for the circumference is .

### Example Question #4 : How To Find The Circumference Of A Circle In Pre Algebra

What is the circumference of a circle with radius ?

Explanation:

Remember, the formula for circumference of a circle is .

Plug in our given values:

### Example Question #5 : How To Find The Circumference Of A Circle In Pre Algebra

If the circumference of a circle is , what is the radius of the circle?

Explanation:

The formula for the circumference of a circle is .

The problem gives us the circumference, so plug that in:

Notice that the 's cancel out:

Divide both sides by :

### Example Question #6 : How To Find The Circumference Of A Circle In Pre Algebra

If the circumference of a circle is , what is the diameter of the circle?

Explanation:

The diameter of the circle is twice the radius, or . We first need to find the radius using the information that has been given to us.

The formula for the circumference of a circle is .

The problem gives us the circumference, so plug that in:

Notice that the 's cancel out:

Divide both sides by :

Plug that into our first equation:

### Example Question #7 : How To Find The Circumference Of A Circle In Pre Algebra

If the diameter of a circle is , what is the circumference?

Explanation:

The formula for circumference is . The problem gives us the diameter instead of the radius, so we need to convert.

The diameter is twice the radius or .

This means that, for this circle, .

Divide both sides by :

Plug this value into our initial equation to solve:

### Example Question #1 : How To Find The Circumference Of A Circle In Pre Algebra

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

Explanation:

The formula for circumference of a circle is .

Plug in our given information and solve.

### Example Question #9 : How To Find The Circumference Of A Circle In Pre Algebra

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

Explanation:

The formula for circumference of a circle is .

Plug in our given values.

### Example Question #10 : How To Find The Circumference Of A Circle In Pre Algebra

What is the circumference of a circle with radius of ?