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McGraw Hill Integrated II, 2012 View details

1. Circles and Circumference

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Exercise 37 Page 720

What is the formula for finding the circumference of a circle?

Diameter: 22.80ft
Circumference: 71.63ft

Practice makes perfect

Let's find the length of the circumference and the diameter separately.

Diameter

To find the diameter, we can multiply the radius by 2. d = 11 25* 2Let's simplify it.

d=11 25* 2

▼

Simplify right-hand side

MixedToFrac

a bc=a* c+b/c

d=(11(5)+2/5)* 2

Multiply

d=(55+2/5)* 2

AddTerms

Add terms

d=(57/5)* 2

Multiply

d=114/5

UseCalc

Use a calculator

d=22.8

Since the exercise asks us to find our answers to the nearest hundredth, this means that the diameter of the circle is 22.80ft.

Circumference

The circumference C of a circle with radius r is calculated using the formula below. C=2π r We know that the radius of the circle is 11 25ft. By substituting 11 25 for r in the formula, we can calculate C.

C=2π r

Substitute

r= 11 25

C=2π( 11 25)

▼

Simplify

MixedToFrac

a bc=a* c+b/c

C=2π(11(5)+2/5)

Multiply

C=2π(55+2/5)

AddTerms