(sin7+cos15sin8)/(cos7+sin15sin8)(2cos10-sin20)/cos20
<p>问题：(sin7+cos15sin8)/(cos7+sin15sin8)(2cos10-sin20)/cos20<p>答案：↓↓↓<p class="nav-title mt10" style="border-top:1px solid #ccc;padding-top: 10px;">耿丽娜的回答：<div class="content-b">网友采纳 (sin7+cos15sin8)/(cos7-sin15sin8) =sin(15-8)+cos15sin8)/(cos(15-8)-sin15sin8) =(sin15cos8-cos15sin8+cos15sin8)/(cos15cos8+sin15sin8-sin15sin8) =(sin15cos8)/(cos15cos8) =sin15/cos15 =tan15 =2-√3 =(2cos10-sin20)/cos20 =/cos20 =(cos30cos20+2in30sin20-sin20)/cos20 =√3
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