Упростить 1)sinB ctgB 2)sin²a/1+cosA 3)cosB tgB+sinB 4)1-cos²a/1-sin²a

Решите задачу:

$1)sin \beta *ctg \beta = \frac{sin \beta *cos \beta }{sin \beta } =cos \beta \\ \\ 2) \frac{sin^{2} \alpha }{1+cosa} \\ \\ 3)cos \beta tg \beta +sin \beta = \frac{cos \beta *sin \beta }{cos \beta } +sin \beta =sin \beta +sin \beta = \\ =2sin \beta \\ \\$

$4) \frac{1-cos ^{2} \alpha }{1-sin^{2} \alpha } = \frac{sin ^{2} \alpha +cos ^{2} \alpha-cos^{2} \alpha }{sin ^{2} \alpha +cos ^{2} \alpha -sin ^{2} \alpha } = \frac{sin^{2} \alpha }{cos^{2} \alpha } = tg^{2} \alpha$