How would I evaluate the following two derivatives.
For this derivative I know $\sin^2+\cos^2(t)=1$
so there derivative of $1$ is $0$
For my second question I have to find the second derivative of $h(t)=\sec(3t)$ at $t=\pi$
I found the first derivative as $3\sec(3t)\tan(3t)$
The second derivative I got
But how would I apply the $\pi$ to the $t$