If the area of an isosceles right angle triangle equals (A)cm2 anf if the rate of change of its area is 32cm/sec at the instant at which the length of each of the equal legs is 8 cm. find (at the instant)the time rate of change of the perimeter (p) of the triangle

Write down your formulae:



l is the length of one side the 'leg'.

P = 2l + h

h is the hypotenuse and is obtained through Pythagoras' Theorem;





You are given

At that time,

You must first the rate at which the length is changing and from there you find the rate at which the perimeter is changing.

You can find dl/dt from the chain rule:



Then you can get the rate of change of perimeter: