I assume that means: Show[tex]\dfrac{1}{\cot a + \tan A} = \sin A \cos A[/tex]Proof:[tex]\dfrac{1}{\cot A + \tan A}[/tex][tex]= \dfrac{1}{\frac{\cos A}{\sin A} + \frac{\sin A}{\cos A}}[/tex][tex]= \dfrac{1}{\frac{\cos^2A + \sin^2 A}{\sin A \cos A}}[/tex][tex]= \dfrac{\sin A \cos A}{\cos^2A + \sin^2 A}[/tex][tex]=\sin A \cos A \quad\checkmark[/tex]