已知sin(π+α)=-1/2则cos(α-3π/2)等于多少?

已知sin(π+α)=-1/2则cos(α-3π/2)等于多少?
已知sin(π+α)=-1/2则cos(α-3π/2)等于多少?

已知sin(π+α)=-1/2则cos(α-3π/2)等于多少?
-1/2
sin(π+α）=-sinα=-1/2
cos(α-3π)=sin(1/2-α+3π/2)=sin(2π-α)=-sinα=-1/2