[tex]\cos \theta(\tan \theta + \cot \theta)\\\\=\cos \theta \tan \theta + \cos \theta \cot \theta \\\\=\cos \theta \left (\dfrac{\sin \theta}{\cos \theta} \right)+ \cos \theta \left(\dfrac{\cos \theta}{\sin \theta} \right)\\\\\\=\sin \theta + \dfrac{\cos^2 \theta}{\sin \theta}\\\\=\dfrac{\sin^2 \theta + \cos^2 \theta}{\sin \theta}\\\\=\dfrac 1{\sin \theta}\\\\=\csc \theta[/tex]
