Calculate ddθ[sin(θ)cos(θ)]\frac{d}{d\theta} [\sin(\theta) \cos(\theta)]dθd[sin(θ)cos(θ)].
cos2(θ)−sin2(θ)\cos^2(\theta) - \sin^2(\theta)cos2(θ)−sin2(θ)
cos2(θ)+sin2(θ)\cos^2(\theta) + \sin^2(\theta)cos2(θ)+sin2(θ)
2cos(θ)2\cos(\theta)2cos(θ)
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