Ex 1. Let A be the area of a square whose sides have length 5 and assume that s varies with the time t. At a certain instant the sides are 3 ft long and increasing at a rate of 2 fit/min. How fast is the area increasmg at that moment? Ex 2. An oil rig springs a leak in calm seas, and the oil spreads in a circular patch around the rig. If the radius of the oil patch increases at a rate of 30 m/hr, how fast is the area of the patch increasing when the patch has a radius of 100 meters