Given A=pi/4 (wh)

Assume that both the width and length of the leaf change with respect to time. Write a expression for the rate of change of the area of the leaf,dA/dt.

Assume that the height of the leaf grows at a rate of 0.7 cm/monthand the width of the leaf grows at a rate of 0.4 cm/month. At what rate is the area increasing when the height of the leaf is 8 cmand the width of the leaf is 6 cm?