Question

How do you prove `arccos(x/2) + arctan(x) = pi/2`?

Answer 1

You can't prove it. It is not always true.

Explanation:

For example, with `x=1`, we get

`arccos(1/2)+arctan(1) = pi/3+pi/4 = (7pi)/12 != pi/2`

It is true only for `x=0`, `x=sqrt3`, and `x=-sqrt3`.