Question

How do you solve for the exact solutions in the interval [0,2pi] of `cos x = 0`?

Answer 1

`x=pi/2` and `x=(3pi)/2`

Explanation:

As seen from the graph of `cosx`, `cosx=0` for `x=pi/2` and `x=(3pi)/2` in the range `0<=x<=2pi`

graph{cosx [-8, 8, -4, 4]}