θ=2π/3 求cosθ 和sinθ 请帮我检查我算得对不对!.2π/3=120度cos120=cos(180-60)=-cos60=-(cos(90-30))=-(-cos30)=cos30=√3/2sin 120 =sin(180-60)=-sin60=-(sin(90-30))=-sin30=-1/2
问题描述:
θ=2π/3 求cosθ 和sinθ 请帮我检查我算得对不对!.
2π/3=120度
cos120=cos(180-60)=-cos60=-(cos(90-30))=-(-cos30)=cos30=√3/2
sin 120 =sin(180-60)=-sin60=-(sin(90-30))=-sin30=-1/2
答