cos120°等于多少

倪狭蒲2634COS120度等于多少? -
边虞先13042373636 ______ cos120 -1/2 满意请采纳

倪狭蒲2634cos120°怎么算?我知道是 - 0.5,我要的是怎么算 -
边虞先13042373636 ______[答案] 原答案是错的,cos120°≠cos(60+60)根据任意角三角函数算有诱导公式:cos(180°-α)=cos(-α)∴cos120°=cos(180°-60°)=-cos60°=-0.5

倪狭蒲2634cos120°怎么算?求过程.谢谢 -
边虞先13042373636 ______ 这个,这是常见角度,应该记住的.cos120=-0.5

倪狭蒲2634cos120度~等于多少!好评 -
边虞先13042373636 ______ cos120=-1/2

倪狭蒲2634cos1200°的值是______. -
边虞先13042373636 ______[答案] cos1200°=cos(360°*3+120°)=cos120°=-cos60°=- 1 2, 故答案为:- 1 2.

倪狭蒲2634cos120°=? -
边虞先13042373636 ______ cos(120°) = -0.5

倪狭蒲2634根号下cos^2 120度等于多少 -
边虞先13042373636 ______[答案] cos120度=-1/2 cos^2 120度=1/4 根号下cos^2 120度= 1/2 或者 根号下cos^2 120度=cos120度的绝对值=1/2

倪狭蒲2634cos120度是好多
边虞先13042373636 ______ cos120度=cos(180度-60度)=-cos60度=-1/2

倪狭蒲2634sin120°=?cos120°=?tan120°=? -
边虞先13042373636 ______[答案] sin120°=sin(180°-60°)= sin60° = 根号3/2 cos120°=cos(180°-60°)= -cos60° = -1/2 tan120°=tan(180°-60°)= -tan60° = -根号3

倪狭蒲2634cos120° =cos(180 - 60)可不可以写成(90+30)?一定要写180吗? -
边虞先13042373636 ______[答案] 可以的,但是不太好 cos120° =cos(180-60) cos120° =cos(90+30) =-sin(30) (不懂问我