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Find the surface area of a sphere when its volumeis changing at the same rate as its radius.A. 1B. `(1)/(2sqrt(pi))`C. `4pi`D. `(4pi)/(3)`

Answer» Correct Answer - A
At any time t, let V, S and r denote respectively the volume, surface area and radius of the sphere. Then,
`V=(4)/(3)pir^(3) and S=4pir^(2)`
`therefore (dV)/(dt)=(dr)/(dt)implies4pir^(2)(dr)/(dt)=(dr)/(dt)implies4pir^(2)=1impliesS=1`


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