Question

Find the x-coordinates of all points on the curve
f(x) = sin 2x − 2 sin x
at which the tangent line is horizontal. (Enter your answers as a comma-separated list. Use n to represent any integer.)

Answer 1

The tangent line is horizontal means you want to know where the derivative is zero.

So find the derivative and set it to zero.

Answer 2

got that, so that the derivative is 2cos(2x)-2cos(x)=0 but where do i go from there