sinα/2=-根号3/3α/2=-arcsin(根号3/3)=2π-arcsin(根号3/3)α=4π-2arcsin(根号3/3)=2π-2arcsin(根号3/3)cosα=cos(2π-2arcsin(根号3/3))=cos(-2arcsin(根号3/3))=cos(2arcsin(根号3/3))=1-2sin^2(arcsin(根号3/...