Question

The base of a triangle is shrinking at a rate of 9cm/s and the height of the triangle is increasing at a rate of 7cm/s. Find the rate at which the area of the triangle changes when the height is 13cm and the base is 4cm.

Answer 1

A = (1/2)*b*h

objective: find dA/dt

given: b = 26, db/dt = 2, b = (1/2)*h

since we are given db/dt lets get area in terms of b

since b = (1/2)h that means h = 2b

so A = (1/2)*b*(2b) = b^2

Take derivative wrt time, t

dA/dt = 2b*db/dt

Explanation: