Question

simplificar (1-secx)(1+secx)

Answer 1

$(1-secx)(1+secx)=1+secx-secx- sec^{2}x =1- sec^{2}x= \\ \\ 1- \frac{1}{cos^{2}x} = \frac{cos^{2}x-1}{cos^{2}x} = \frac{-sen^{2}x}{cos^{2}x} = \\ \\- tan^{2}x$