$$\int \frac{1}{\left(x^2+1\right)^2} d x=\ldots$$

If $\theta=\frac{17 \pi}{3}$ then, $\tan \theta-\cot \theta=\ldots$

Derivative of $\log _{e^2}(\log x)$ with respect to $x$ is

In $\triangle A B C$; with usual notations, if $\cos A=\frac{\sin B}{\sin C}$ then the triangle is ............