Ap calculus Ab *plz help a friend out*

Question

A right triangle has legs of 36 inches and 48 inches whose sides are changing. The short leg is increasing by 6 in/sec and the long leg is shrinking at 8 in/sec. What is the rate of change of the area?

Answer 1

The area if a triangle is base × height ÷ 2.

Let b be the short leg with db/dt = 6 in/sec

Let h be the long leg with dh/dt = -8 in/sec

A = bh/2

The problem is asking for dA/dt when b = 36 and h = 48

dA/dt = (1/2)(b dh/dt + db/dt h) By the product rule

= (1/2)(36(-8) + 6(48)) = (-288 + 288)/2 =0

The area isn't changing.