Question

(sin a-sin b)/(cos a+cos b), если a-b=Π/2

Answer 1

$a-b=frac{pi}{2}quad Rightarrow quad a=frac{pi}{2}+b\\ frac{sina-sinb}{cosa+cosb} = frac{sin(frac{pi}{2}+b)-sinb}{cos(frac{pi}{2}+b)+cosb} = frac{cosb-sinb}{-sinb+cosb} =1$