$\tan h^{-1}\left(\frac{1}{2}\right)+\cot h^{-1}\left(2\right)$ is equal to
 

Which of the following identitiy is not true?

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$

Prove the following hyperbolic identity, 

$\sinh 3x\equiv 3\sinh x+4{\sinh }^{3}x$