Question

When `cosx=1`, what does `x` equal?

Answer 1

`x` can be any integer multiple of `2pi`, including `0`

Explanation:

The function `cos(x)` has period `2pi` and `cos(0) = 1`

Hence:

`cos(2npi) = 1" "` for any integer `n`

graph{cos(x) [-10, 10, -5, 5]}