Question

Срочно помогите ПЖ ​

Answer 1

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