Вычислить. sin a (5 cos+2) / (10 cos a + 4) * cos a? если tg a = 5

1. а) (sina+cosa) / (2sina-cosa) = [cosa * (tga+1) ] / [cosa * (2tga-1) ] = (tga+1) / (2tga-1) = (5/4+1) / (2*5/4-1) = (9/4) / (6/4) = 9/6=1,5 2) а) 1 - sin2 a + ctg2 a * sin2 a = cos2a+cos2a / sin2a = cos2a+cos2a=2*cos2a