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已知sin(派+α)=m,则sin(3派-α)= 已知cosα=7分之派,且α∈[-派,0],则角α=
人气:178 ℃ 时间:2020-03-24 06:49:02
解答
sin(π+α)=m
sin(3π-α)=sin{2*2π-(π+α)} = -sin(π+α) = -m
cosα=π/7>0
α∈[-π,0]
α = -arccos(π/7)
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