Here is another tutorial with animations and a problem set. You can do as many questions from the problem set as you like. You may also want to try the first 5 questions here. Answers are provided so see if you can solve them without looking at the answers. ;-)

All of that is just too get extra help if you need it. This is your homework:

The Three Questions:

(1) As a circular metal griddle is being heated, its diameter changes at a rate of 0.01 cm/min. Find the rate at which the area of one side is changing when the diameter is 30 centimeters.

Answer: 0.15π cm/min

(2) A stone is dropped into a lake, causing circular waves whose radii increase at a constant rate of 0.5 m/sec. At what rate is the circumference of a wave changing when its radius is 4 meters?

Answer: π m/sec

(3) The ends of a water trough 8 feet long are equilateral triangles whose sides are 2 feet long. If water is being pumped into the trough at a rate of 5 ft^{3}/min, find the rate at which the water level is rising when the depth of the water is 8 inches.

Answer: (15/32)√(3) ft/min

## 1 comment:

Hi,

Could we go over the third one? I've tried it a couple times but im getting a different answer..

THanks

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