Find the derivative of f(x)=cos2(x)−sin2(x)f(x) = \cos^2(x) - \sin^2(x)f(x)=cos2(x)−sin2(x).
−2sin(2x)-2 \sin(2x)−2sin(2x)
2sin(2x)2 \sin(2x)2sin(2x)
−4sin(2x)-4 \sin(2x)−4sin(2x)
000