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sin(5π/3)等于多少?怎么求的?

sin(5π/3)=-sin(π/3) = -√3/2 cos(5π/3)=cos(π/3) = 1/2 tan(5π/3)=-tan(π/3) = -√3

可以用诱导公式阿 sin5π/6=sin(π-π/6)=sinπ/6 或者画正弦函数图像 借助图像很清晰又很快

奇变偶不变,符号看象限

sin(α-π)=3/5 sin(π-α)=-3/5 sinα=-3/5 cos2α=1-2sin²α =1-18/25 =7/25

sin(-35π/17)=sin(-2π-π/17)=-sin(π/17) 这样对吧。

sin2/3π=√3/2 sin5/6π=1/2 sin7/6π=-1/2 sin(-π/3)=-√3/2

-4/3 解析: tan(θ-π/4) =-tan(π/4-θ) =-cot[π/2-(π/4-θ)] =-cot(π/4+θ) =-cos(π/4+θ)/sin(π/4+θ) =-4/3

sin4π/3 * cos25π/6 * tan5π/4 ﹦-sin60·cos30·tan45 ==-√3/2×√3/2×1 =-3/4

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