00:01
In part a, we want to find the rate of change of the revenue, which is just the derivative of the revalu function.
00:09
So we take derivatives to the revalo function.
00:13
We use a chain rule.
00:15
The derivative of pi t over 6 is just pi over 6, and it equals minus 3 times pi over 6.
00:29
And the derivative of cosine x is minus sine x, and hence times minus sine pi t over 6.
00:45
And we can rewrite the derivative as pi over 2 times sine pi t over 6.
00:53
For part b, we just evaluate the value of the derivative at 1, 6 and 11.
01:00
And their derivative values are minus .785 and point .785 respective.
01:16
For per c, we want to find the local maximum and local minimum, and hence we need to find the critical numbers...