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A stone is dropped into a quiet lake and...

A stone is dropped into a quiet lake and waves move in circles at the speed of 5 cm/sec. At that instant, when the radius of circular wave is 8 cm, how fast is the enclosed area is increasing

A

`6pi (cm^(2))/s`

B

`8pi (cm^(2))/s`

C

`8/3 (cm^(2))/s`

D

`80pi (cm^(2))/s`

Text Solution

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The correct Answer is:
D
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