- упростите выражение

Решите задачу:

$\frac{cos \beta }{1-sin \beta } - \frac{cos \beta }{1+sin \beta } = \frac{cos \beta *(1+sin \beta )-cos \beta *(1-sin \beta )}{(1-sin \beta )(1+sin \beta )} =$ $\frac{cos \beta +sin \beta *cos \beta -cos \beta +sin \beta*cos \beta }{1-sin^2 \beta }= \frac{2*sin \beta *cos \beta }{cos^2 \beta } = \frac{2sin \beta }{cos \beta } =2tg \beta$