Let s = cos (theta). Evaluate ds/dt when theta= $\displaystyle \frac {3pi}{2}$ and dtheta/dt= 5.
I have no clue what they want me to do.
The answer is 5
Hello,
you have:
$\displaystyle s=\cos(\theta)$ . Now derivate wrt t. Use chain rule!:
$\displaystyle \frac{ds}{dt}=-\sin(\theta) \cdot \frac{d \theta}{dt}$
Plug in the values you know:
$\displaystyle \frac{ds}{dt}=-\sin\left(\frac {3\pi}{2} \right) \cdot 5$
Since $\displaystyle -\sin\left(\frac {3\pi}{2} \right) = 1$ the result is 5.