Question

упростите cosx/1-sinx + cosx/1+sinx

Answer 1

Решение
cosx / (1 -sinx) + cosx / (1 + sinx) =( cosx(1 +sinx + 1 - sinx)) / (1 - sin^2x) = 
(2cosx) / (1 - sin^2x) = (2cosx) / (cos^2x) = 2 / (cosx)