Question

упростить sina/(1+cosa) + sina/(1-cosa)

Answer 1

$\frac{sina}{1+cosa}+ \frac{sina}{1-cosa} = \frac{sina(1-cosa)+sina(1+cosa)}{(1+cosa)(1-cosa)} = \\ =\frac{sina-sinacosa+sina+sinacosa}{1-cos^2a} = \frac{2sina}{sin^2a} = \frac{2}{sina}$