## Questions and Answers

What is the derivative of $f(x)=\frac{\sin x}{1+\cos x}\cdot \tan^3x$?

$f'(x)=\frac{2\sin^2x}{(1+\cos x)^2}$

At which points is the function $f(x)=\frac{\sin x}{1+\cos x}\cdot \tan^3x$ undefined?

$x=\frac{\pi}{2}+k\pi, : k\in \mathbb{Z}$

What is the limit of $f(x)=\frac{\sin x}{1+\cos x}\cdot \tan^3x$ as $x$ approaches $\frac{\pi}{2}$?

The limit is $\infty$