已知0<α<π/2<β<π,COSα=3/5,SIN(α+β)=-3/5,则COSβ=

问题描述:

已知0<α<π/2<β<π,COSα=3/5,SIN(α+β)=-3/5,则COSβ=

∵COSα=3/5,0<α<π/2,
∴sinα=4∕5
∵SIN(α+β)=-3/5