Question

please Solve this for me.

Answer 1

2nd line comes from ----

$2 \tan^{ - 1} x = \sin^{ - 1} \frac{2x}{1 + x^{2} } \\ = \cos^{ - 1} \frac{1 - x^{2} }{1 + x^{2} } = \tan^{ - 1} \frac{2x}{1 - x ^{2} }$


4th line comes from ----

$\tan^{ - 1} x - \tan^{ - 1} y = \tan ^{ - 1} \frac{x - y}{1 + xy}$



Hope it will help you .