NettFind the critical points of: y = x+cos(x) https://math.stackexchange.com/q/124497. You're essentially there: y = x+cos(x)= 2π +2πk+cos(2π +2πk)= 2π +2πk. There are infinitely many y -values, one for each k ∈ Z. Solve cos2x−sinx= 0 for 0 ≤ x≤ 360.