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Find the rate of change of the area of c...

Find the rate of change of the area of circle w.r.t.r when r=8 cm.

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Let radius =r cm. `therefore` Area of the circle `A=pir^2rArr(dA)/dr=2pir` The rate of change of area for r=8 is `(dA)/(dr)]_(r=8)=[2pir]_(r=8)=16picm^2//cm`
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