Question

How do you evaluate `cos^-1 (-.6466)`?

Answer 1

In degree `cos^-1(-0.6466)=130.2857^0(4dp)`
In radian `cos^-1(-0.6466)=2.2739(4dp)`rad.

Explanation:

Let `theta=cos^-1(-0.6466) :. cos theta= (-0.6466)` Using calculator for inverse of `cos` we get `theta=130.2857^0(4dp) or theta= 2.2739 (4dp)` radian [Ans]