Q3 of 78 Page 13

The side of a square is increasing at the rate of 0.2 cm/sec. Find the rate of increase of the perimeter of the square.

Given: the side of a square is increasing at the rate of 0.2 cm/sec.


To find rate of increase of the perimeter of the square


Let the edge of the given cube be x cm at any instant time.


Then according to the given criteria,


Rate of side of the square increasing is,


Then the perimeter of the square at any time t will be


P = 4x cm.


Applying derivative with respect to time on both sides we get,




[from equation(i)]


Hence the rate of increase of the perimeter of the square will be 0.8cm/sec


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