Question

1-tgx/1+tgxрЕБЯТ ПОМОГИТЕ

Answer 1

$\frac{1-tgx}{1+tgx} = \frac{1- \frac{Sinx}{Cosx} }{1+ \frac{Sinx}{Cosx} }= \frac{ \frac{Cosx-Sinx}{Cosx} }{ \frac{Cosx+Sinx}{Cosx} } = \frac{Cosx-Sinx}{Cosx+Sinx}$