An outside circular ring has a circumference of 90 cm. What is the circumference of an inner ring which is 8 cm shorter in radius? Both circles have the same center. 39.8 correct?

Question

An outside circular ring has a circumference of 90 cm. What is the circumference of an inner ring which is 8 cm shorter in radius? Both circles have the same center.  39.8 correct?

anonymous · Answer

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anonymous · Answer

|dw:1337928450924:dw|

anonymous · Answer

Circumference = 90
Radius = 90/(2*pi) => 90/6.28 = ?

maheshmeghwal9 · Answer

ya it is correct @suzy4321

maheshmeghwal9 · Answer

I know u have calculated outer circle's radius & then subtract 8 & got inner circle's radius.
then u found circumference of inner circle by the fomula as:)
$$2\pi r$$

maheshmeghwal9 · Answer

& the answer u got $$39.76\approx39.8$$ is correct:)

anonymous · Answer

39.7

anonymous · Answer

okay thanks everyone

anonymous · Answer

My drawings with the calculation I showed are more useful I think. Anyway, all is well!!

anonymous · Answer

GT that is why u got three medals