原式=[sin(30°+13°)-sin13°cos30°]/cos13°
=(sin30°cos13°+cos30°sin13°-sin13°cos30°)/cos13°
=sin30°cos13°/cos13°
=sin30°
=1/2
化简:sin43°-sin13°cos30°/cos13°
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相关问题
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cos43°cos13°+sin43°sin13°的值等于 ___ ．
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计算sin43°cos13°-cos43°sin13°的值为______．
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计算sin43°cos13°-cos43°sin13°的值为______．
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sin43度cos13度减sin13度cos43度等于多少
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sin43°cos13°-cos43°sin13°= A：1/2 B：根号3/3 C：根号2/2
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sin13°cos17°+cos13°sin17°=______．
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sin13°cos17°+cos13°sin17°=______．
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sin²13°＋cos²17°－sin13°cos17°=?
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（sin13度＋sin17度×cos30度）/(cos13度－sin17度×sin30度)＝多少
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化简 (13 9:27:46)化简：(1+sin2a-cos2a)/(1+cos2a+sin2a)