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Cos150度等于多少啊

cos150°=cos(120°+30°)=cos120°cos30°-sin120°sin30°=(-1/2)x√3/2-√3/2x1/2=-√3/4-√3/4=-(√3+√3)/4=-2√3/4=-√3/2 ≈-0.866 答题不易,望采纳~~~~

cos150°=cos(180°-30°)=-cos30°=负2分之根号3.这是根据必修四里面的公式:cos(π-α)=-cosα 望采纳

cos150=cos(180-30)=cos180*cos30+sin180*sin30=-1*二分之根号三+0*二分之一=负二分之根号三

cos150=cos(90+60)=cos90*cos60-sin90*sin60=0-根号3/2=-根号3/2

COS150度=-COS30度=-根号3/2 SIN150度=SIN30度=1/2

cos150°=-cos30°=-√3/2望采纳

-cos 30度 等于负二分之根号三

cos150°=cos(180°-30°)=-cos30°=-√3/2

cos150=cos(90+60)=cos90*cos60-sin90*sin60=0-根号3/2=-根号3/2

COS150度=-COS30度=-二分之根号三

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