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# Find the radius of a circle with a circumference of 64 pi inches.?

How do you get that so I can jot down for future reference. I know the A= pi r^2 but cant get this one.

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- Donnie PorkoLv 77 months agoFavorite Answer
Circumference = 2🥧r (sorry, I can’t do pi on my iPhone and I didn’t want you to confuse it as p*i).

64🥧 = 2🥧r

r = 32

- Anonymous7 months ago
c = 2πr

64π = 2πr

Cancel π

64 = 2r

32 = 1r

r = 32

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- Anonymous7 months ago
C = 2 pi R

C = pi D

pi = 3.14

pi = 22/7

Substitute given values into equation

64 = 2 X 3.14 X R

64/ 6.28 = R

10.19 = R

The radius is 10.19 inches

You can also use estimation to get you in the right ballpark

Circumference is about 6 times the length of the radius or about 3 times the diameter

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- 🐭-LAB RAT-🐭Lv 67 months ago
d = circ/pi = D 20.38 divided by 2 = r 10.19

"d = circ/pi = D 20.38 divided by 2 = r 10.19" — How does 64π / π = 20.38 ?

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It's correct! =)