[tex]a)\ \sin x\cos x\\\\b)\ \dfrac{1}{2}\sin(2x)=\dfrac{1}{2}\cdot2\sin x\cos x=\sin x\cos x\\\\c)\ \sin^2x\cot^2x=\sin^2x\cdot\dfrac{\cos^2x}{\sin^2x}=\cos^2x\\\\d)\ \tan x\cos^2x=\dfrac{\sin x}{\cos x}\cdot\cos^2x=\sin x\cos x\\\\Answer:\ c).[/tex]
