Question

Find dc of 1-cosx/1+cosx​

Answer 1

Go through this.

This will help you out.

Answer 2

ANSWER :-

$\frac{d}{dx} (\frac{1-cos(x)}{1+cos(x)} )=\frac{d}{dx}(\frac{2sin(\frac{x}{2}) }{2cos(\frac{x}{2} )} )\\\implies\frac{d}{dx} (tan(\frac{x}{2} ))\\\implies\frac{1}{cos^{2}(\frac{x}{2}) } =sec^{2} (\frac{x}{2})$

HOPE THIS HELPS YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!