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10. The formula for the circumference of a circle with diameter d is C = d.

a. Solve the formula for d.
b. The circumference of a circle is 8 inches. What is the diameter of
the circle?
c. The circumference of a circle is 61 inches. What is the radius of
the circle?

User Tensho
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1 Answer

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Answer:

a. d = C/π

b. d = 8/π inches ≈ 2.546 inches

c. r = 61/(2π) inches ≈ 9.708 inches

Explanation:

a. The formula for circumference is ...

C = πd

Dividing by π gives ...

d = C/π

__

b. For a circumference of 8 inches, the diameter is ...

d = (8 in)/π = (8/π) in ≈ 2.546 in

__

c. The radius is 1/2 the diameter. So, the radius of a circle is ...

r = d/2 = (C/π)/2 = C/(2π)

For a circumference of 61 inches, the radius is ...

r = (61 in)/(2π) = 61/(2π) in ≈ 9.708 in

User BigJoke
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