cos140°等于多少

滕解修2870cos140°比sin40°怎么算
张药眉18059723000 ______ cos140°/sin40°=cos(180°-40°)/sin40°=-cos40°/sin40°=-cot40° 希望能帮到你,祝学习进步

滕解修2870已知sin220°=k ,求cos140°和tan140° -
张药眉18059723000 ______[答案] sin220=sin-140=-sin140=k (cos140)^2=1-(sin140)^2 cos140= - 根号(1-(-k)^2) tan140=sin140/cos140 =k*(根号(1-k^2))/(1-k^2)

滕解修2870求值cos100°cos140°cos160°. -
张药眉18059723000 ______[答案] cos100°cos140°cos160°=-cos20°cos40°cos80° =- sin20°cos20°cos40°cos80° sin20°=- 1 8

滕解修2870cos20°+cos100度+cos140度=? -
张药眉18059723000 ______[答案] cos20°+cos100°+cos140° =2cos( 20°+100°/2)cos( 20°-100°/2)+cos140° =2cos60°cos40°+cos(π-40°) =cos40-cos40° =0

滕解修2870cos20+cos40+cos140+cos100全部是度数 -
张药眉18059723000 ______[答案] Cos[20 °] + Cos[40 °] + Cos[140 °] + Cos[100 °] =Cos[20 °] - Sin[10 °]

滕解修2870若cos140°=a,则sin220的值为? -
张药眉18059723000 ______[答案] sin220 =sin(40+180) =-sin40 =-sin(180-140) =-sin140 =-√(1-cos²140) =-√(1-a²)

滕解修2870cos150°等于多少?用分数表示 -
张药眉18059723000 ______[答案] 解 cos150°=cos(180°-30°)=-cos30°=-√3/2

滕解修2870sin120°= cos120°=sin60°= cos60°=sin150°= cos150°=sin30°= cos30°=sin140°= cos140°=sin40°= cos40°=1.规律是什么?2.若设a为锐角,则这个规律... -
张药眉18059723000 ______[答案] sin120°= 根号3/2 cos120°=-0.5sin60°= 根号3/2 cos60°=0.5sin150°= 0.5 cos150°=-根号3/2 sin30°= 0.5 cos30°=根号3/2 sin140°= 0.643 cos140°=-0.766sin40°= 0.643 cos40°=0.766(1)sin120°= sin60...

滕解修2870余弦一百五十度等于多少 -
张药眉18059723000 ______[答案] cos150°=-cos30°=-√3/2

滕解修2870cos20°+cos60°+cos100°+cos140°=? -
张药眉18059723000 ______[答案] Cos20°+ Cos 60°+ Cos100°+ Cos140° =(Cos20°+Cos140°)+(Cos60°+Cos100°) =[cos(80-60)+cos(80+60)]+[cos(80-20)+... =2Cos80°Cos60° + 2Cos80°Cos20° =2Cos80°(Cos60°+Cos20°) =4Cos80°Cos40°Cos20° =(4Cos80°Cos40°Cos20°Sin...