By using the identities tanθ=sinθcosθ\displaystyle \tan \theta = \frac{\sin \theta}{\cos \theta}tanθ=cosθsinθ and secθ=1cosθ\displaystyle \sec \theta = \frac{1}{\cos \theta}secθ=cosθ1, and the standard derivatives of sinθ \sin \theta\,sinθ and cosθ\cos \thetacosθ, prove the following results: