Trigonometry
Write the following expression in terms of θ\thetaθ only. Use the identity for the cosine of a sum.
cos(θ+π2)\cos\left(\theta+\frac{\pi}{2}\right)cos(θ+2π)
−cosθ-\cos\theta−cosθ
−sinθ-\sin\theta−sinθ
cos2θ\cos2\thetacos2θ
−2sinθ-2\sin\theta−2sinθ