Respuesta :

LammettHash
[tex]\cos^4x=\cos^4x\csc x[/tex]
[tex]\cos^4x-\cos^4x\csc x=0[/tex]
[tex]\cos^4x(1-\csc x)=0[/tex]
[tex]\implies \begin{cases}\cos^4x=0\\1-\csc x=0\end{cases}\implies x=\dfrac\pi2,\dfrac{3\pi}2[/tex]