Question

(1-cosa) /sina = tg(a/2) Доказать равенство

Answer 1

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