Respuesta :

[tex] \cot(x)=\frac{\cos x}{\sin x} [/tex]

$\sec x=\frac1{\cos x}$

$\therefore \cot^2x\cdot\sec^2x= \frac{\cos^2x}{\sin^2x}\frac{1}{\cos^2x}=\frac{1}{\sin^2x}$