i need help with these problems
i really dont understand how to do them
1.
[2sin (x)]/[1-cos^2(x)]
i really appreciate your help
$\displaystyle sin^2(x)+cos^2(x)=1$ is a well known identity (one that must be memorized)
So subtract $\displaystyle cos^2(x)$ from both sides to get $\displaystyle sin^2(x)=1-cos^2(x)$ so....
$\displaystyle \frac{2sin(x)}{1-cos^2(x)}=\frac{2sin(x)}{sin^2(x)}=\frac{2}{sin(x) }=2\csc(x)$