Question

2tan-¹(-1/3)+cos-¹(3/5)=π/2​

Answer 1

There is some error in the question.

$2 \tan ^{ - 1} ( - \frac{1}{3} ) + \cos ^{ - 1} ( \frac{3}{5} ) ≠ \frac{ \pi} {2}$

But,

$2 \tan ^{ - 1} ( + \frac{1}{3} ) + \cos ^{ - 1} ( \frac{3}{5} ) = \frac{ \pi} {2}$

And,

$2 \tan ^{ - 1} ( - \frac{1}{3} ) - \cos ^{ - 1} ( \frac{3}{5} ) = - \frac{ \pi} {2}$