# How to Find the Radius of a Circle: Definition & Formula

Instructions:

question 1 of 3

### If the diameter of a circle is 10, what is the length of a radius of that circle?

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### 2. You know the area of a pizza pie is 154 square inches. What is the radius of that pizza pie?

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This quiz and corresponding worksheet will help you gauge your knowledge of finding the radius of a circle. Topics you'll need to know to pass the quiz include understanding the method to calculate the length of the radius of a given circle.

## Quiz & Worksheet Goals

Use this printable worksheet and quiz to review:

• Solving for radius given circumference or diameter
• Determining radius when given the area
• Identifying how a minute hand of a clock could be described

## Skills Practiced

This worksheet and quiz will let you practice the following skills:

• Defining key concepts - ensure that you can define main concepts, such as diameter, circumference, and radius
• Problem solving - use acquired knowledge to solve for the radius

To learn more about how to calculate half the length of a circle, review the corresponding lesson titled, How to Find the Radius of a Circle: Definition & Formula. This lesson will help you:

• Define what the radius of a circle is
• Understand how the radius relates to the circumference
• Show the process to get the diameter from the radius
• Identify the formula to calculate a circle's area
• Describe what radii in real life could look like
• Appreciate how to solve for the radius of any circle
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