Question

$\text{If}f\left(x\right)=\cos ux+\cot x,\text{find}{f}^{\prime }\left[\frac{\pi }{4}\right]$

Answer 1

$f\left(x\right)=cosux+cotx$

$f^{\prime }\left(x\right)=-sinux.4+(-\frac{1}{si{n}^{2}x})$

$f\left(\frac{\pi }{u}\right)=-usin\frac{\pi u}{4}-cose{c}^2\frac{\pi }{4}$

$=-usin\frac{u\pi }{4}-2$