因为sin(185-45)=sinx140,sinx140=sin45
为什么sin(180-45)=sin45
4个回答
相关问题
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为什么sin(45-30)=sin45*cos30-sin30*cos45?
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sin2120°+cos180°+tan45°-cos2(-330°)+sin(-210°)=______.
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sin2120°+cos180°+tan45°-cos2(-330°)+sin(-210°)=______.
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sin2120°+cos180°+tan45°-cos2(-330°)+sin(-210°)=______.
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如果α∈(90°,180°)且sinα=4/5,那么sinα+45°)+cos(α+45°)等于
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cos(45+30)cos(45-30)+sin(45+30)sin(45-30=)
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sin45°×cos60°+sin45°
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sin(45+&)sin(45-&)=1/6,90>&
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(cos 45°-sin 30°)/(cos 45°+sin 30°)
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(1)求值sin2120°+cos180°+tan45°-cos2(-330°)+sin(-210°)