Sin(α-π/4) , если cosα=-0.6, π/2<α<π.
Sin(a-p/4) cosa=-0.6 p/2найдем Sina 1-cost^2=sin^t sin^2=(1^2-6/10^2)=(1-36/100)=(100-36/100)=64/100( извлекли из квадрата ) sina=8/10 cosa=-0.6 sina*cos(-p/4)+cosa*sin(-p/4) sina*cosp/4+cosa*sin(-p/4) 8/10*√2/2+(-6/10*-√2/2)⇒ 4√2/10+3√2/10=4√2+3√2/10