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Pearson Geometry Common Core, 2011

PG

Pearson Geometry Common Core, 2011 View details

5. Volumes of Pyramids and Cones

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Exercise 45 Page 732

Do you remember the formula for the area of a circle?

7.1in.^2

Practice makes perfect

The area of a circle with radius r is calculated using the formula below. A=π r^2To use the formula, we first need to divide the diameter by 2 to determine the radius. r=d/2 ⇒ r=3/2 r= 1.5in. Now, we know that the radius of the circle is 1.5in. By substituting 1.5 for r in the formula, we can calculate the area A.

A=π r^2

r= 1.5

A=π( 1.5)^2

Calculate power

A=π(2.25)

Use a calculator

A=7.068583...

Round to 1 decimal place(s)

A≈ 7.1

The area of the circle is approximately 7.1 square inches.

Subchapter links

Lesson Check p.729

Practice and Problem-Solving Exercises p.729-732

Standardized Test Prep p.732

Mixed Review p.732