Respuesta :

Answer:

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