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Big Ideas Math Geometry, 2014

BI

Big Ideas Math Geometry, 2014 View details

7. Surface Areas and Volumes of Cones

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Exercise 28 Page 646

Use the formula for the area of a circle.

380.13 cm^2

Practice makes perfect

The area of a circle with radius r is calculated using the formula below. A=π r^2From the exercise, we know that the diameter of the circle is 22cm. To use the formula we first need to divide the diameter by 2 to determine the radius. r=22/2=11 Now, by substituting 11 for r in the formula we can calculate A.

A=π r^2

r= 11

A=π( 11)^2

▼

Evaluate right-hand side

Calculate power

A=π * 121

Use a calculator

A=380.13271 ...

Round to 2 decimal place(s)

A≈380.13

The area of the circle is approximately 380.13 cm^2.

Subchapter links

Communicate Your Answer p.641

Monitoring Progress p.642-644