Question

How do you solve `cosx=-sqrt2/2`?

Answer 1

The answers are `S={3/4pi+2kpi ,5/4pi+2kpi}`, `k in ZZ`

Explanation:

`cosx=-sqrt2/2`

The angle is in the second and third quadrant

`x=3/4pi+2kpi (k in ZZ)`

and

`x=5/4pi+2kpi(k in ZZ)`