Question

How do you calculate `tan(cos^-1(-3/5))`?

Answer 1

`tan(cos^(-1)(-3/5)) = +- 4/3`

Explanation:

If `cos(theta) = -3/5`
then `theta` must be one of the angles indicated in the diagram below (either in the second or third quadrant).

Both associate triangles are standard `3-4-5` right angled triangles
and depending upon whether the angle is in the second or third quadrant,
the `tan` will be either `4/5` or `-4/5`