Please answer each of these questions to the best of your ability. You are welcome to re-watch parts of any of the videos to help you.

A rectangle has a constant height of 6 cm, as shown below. The area of the rectangle is given by the formula , where is the length of the base of the rectangle and is the height of the rectangle. In order to determine how fast its area is changing at the instant that the base has length 8 cm, which of the following formulas would you use?


A submarine is diving at a rate of 50 feet per minute. As the sub descends, the water temperature outside is falling at a rate of 0.5 degrees per foot. Let D be the depth of the submarine. Let T be the temperature outside the submarine. How quickly is the temperature falling? If your answer is that we need to know the depth and/or temperature, type NEI for not enough information.

degrees per minute

A circle’s radius, , is increasing at a rate of 3 inches per second, as shown below. How quickly is its area increasing? (The formula for the area of a circle is .)