Question

(a) If A is the area of a circle with radius r and the circle expands as time passes, find dA/dt in terms of dr/dt (b)Suppose oil spills from a ruptured tanker and spreads in a circular pattern. If the radius of the oil spill increases at a constant rate of 2 m/s, exactly how fast (in m^2/s) is the area of the spill increasing when the radius is 33 m?

Fig: 1

Fig: 2