Question

Срочно помогите!!!!!!!!!!!!!!!!!!!

Answer 1

$\frac{2sin \alpha -sin2 \alpha }{(1-cos \alpha )cos \alpha }=\frac{2sin \alpha -2sin \alpha \cdot cos \alpha }{(1-cos \alpha )cos \alpha }=\frac{2sin \alpha (1-cos \alpha )}{(1-cos \alpha )cos \alpha }=\frac{2sin \alpha }{cos \alpha }=2tg \alpha$