Envision Math 2.0: Grade 7, Volume 2
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Envision Math 2.0: Grade 7, Volume 2 View details
5. Solve Problems Involving Circumference of a Circle
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Exercise 8 Page 445

The radius of a circle is half the length of the diameter.

62.8ft

Practice makes perfect

Let's look at a circle with the given diameter.

The diameter is 20 ft. Remember that the radius is half the length of the diameter, so let's divide the diameter by 2. r=20 ÷ 2 = 10 This means that the radius of the circle is 10 cm. Remember that the circumference of a circle with radius r is calculated using the formula below. C=2π r By substituting 10 for r in the formula, we can calculate C. We will use 3.14 for π.
C=2Ď€ r
C=2Ď€( 10)
C=62.8
The circumference of the circle is approximately 62.8ft.

Extra

More About Circles!

Are you interested in learning more about circles? Our Mathleaks original content can teach you all about them! Check out the following resources to see real-world uses for circumference and area, how circles compare to other shapes and why, as well as some higher level topics that you can look forward to learning about in Geometry and Algebra 2.