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已知cos(80°+θ)=1/3,求cos(260°+θ)+1/sin(-350°-θ)的值
人气:426 ℃ 时间:2020-05-25 20:18:20
解答
cos(260°+θ)+1/sin(-350°-θ)
=-cos(80°+θ)+1/sin(10-θ)
= -cos(80°+θ)+1/cos(80°+θ)
=-1/3+3
=8/3
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