Envision Math 2.0: Grade 7, Volume 2
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Envision Math 2.0: Grade 7, Volume 2 View details
6. Solve Problems Involving Area of a Circle
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Exercise 5 Page 452

Use the formula for finding the area of a circle.

3ft

Practice makes perfect

We want to find the radius of a circle with area of 28.26 square feet.

Remember that the area of a circle with radius r is calculated using the formula below. A=π r^2 Since the area of the circle is 28.26ft^2, we can substitute 28.26 for A in the formula and solve the resulting equation for r. We will use 3.14 for π.
A=Ď€ r^2
28.26=Ď€ r^2
28.26/Ď€=Ď€ r^2/Ď€
28.26/Ď€=Ď€ r^2/Ď€
28.26/Ď€=r^2
9 =r^2

Write power as a product

9= r * r
Note that the only number that after multiplying by itself equals 9 is 3. This means that the radius of the circle must be 3ft.

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.