Relax

Respuesta :

[tex]\dfrac{1-\sin x}{\cos x}=\dfrac{\cos x}{1+\sin x}\\ \cos^2 x=(1-\sin x)(1+\sin x)\\ \cos^2 x=1-\sin^2 x\\ \sin^2 x+\cos ^2 x=1[/tex]

It IS the identity.