What is the derivative of f(x)=cos(2x)f(x) = \cos(2x)f(x)=cos(2x)?
−2sin(2x)-2\sin(2x)−2sin(2x)
2sin(2x)2\sin(2x)2sin(2x)
−sin(2x)-\sin(2x)−sin(2x)
−2cos(2x)-2\cos(2x)−2cos(2x)