Question

How do you find the exact value of `arctan [cos(-5pi/6)]`?

Answer 1

`40.893^o` or `0.714` radians

Explanation:

As `cos(-5pi/6)=-sqrt3/2=-0.866`,

`arctan[cos(-5pi/6)]` is an angle `theta` so that

`tantheta=-0.866` and

`theta=arctan(-0.866)=40.893^o` or `0.714` radians