Упростите: 2sin2a-1/sina+cosa

[latex] \frac{2sin2a-1}{sina+cosa} = \frac{2sinacosa-1}{sina+cosa} = \frac{2sinacosa-sin^{2} a-cos^{2} a}{sina+cosa} = \\ =- \frac{sin^{2} a+cos ^{2} a-2sinacosa}{sina+cosa}=- \frac{(sina+cosa)^{2} }{sina+cosa} =-(sina+cosa)= \\ =-sina-cosa[/latex]