Question

tg a=3,Обчислити sina-cosa/sina+cosa

Answer 1

$\frac{\sin \alpha -\cos \alpha }{\sin \alpha +\cos \alpha} =\frac{(\sin \alpha -\cos \alpha)/\cos \alpha }{(\sin \alpha +\cos \alpha) /\cos \alpha} = \frac{tg \alpha -1 }{tg \alpha +1}=\frac{3 -1 }{3 +1}=\frac{2 }{4}=0.5$