Question

Помогите решить под а и б срочно

Answer 1

$\frac{1+cos2a}{2\, cosa}=\frac{2cos^2a}{2\, cosa}=cosa\\\\\\\frac{sin2\beta }{1+cos2\beta }=\frac{2\, sin\beta \, cos\beta }{2cos^2\beta }=\frac{sin\beta }{cos\beta }=tg\beta \\\\\\\frac{1-cos2\beta }{2sin\beta }=\frac{2sin^2\beta }{2\, sin\beta }=sin\beta$