如图,一道化简题求详解

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/24 09:35:17
如图,一道化简题求详解如图,一道化简题求详解如图,一道化简题求详解原式=[sin(15-8)+cos15sin8]/[cos(15-8)-sin15sin8]=(sin15cos8-cos15sin8

如图,一道化简题求详解
如图,一道化简题

求详解

如图,一道化简题求详解
原式=[sin(15-8)+cos15sin8]/[cos(15-8)-sin15sin8]
=(sin15cos8-cos15sin8+cos15sin8)/(cos15cos8+sin15sin8-sin15sin8)
=(sin15cos8)/(cos15cos8)
=sin15/cos15
=(sin15cos15)/(cos15cos15)
=sin30/(1+cos30)
=1/(2+√3)
=2-√3

原式=[sin(15°-8°)+cos15°sin8°]/[cos(15°-8°)+sin15°sin8°]
=(sin15°cos8°-cos15°sin8°+cos15°sin8°)/(cos15°cos8°-sin15°sin8°+sin15°sin8°]
=sin15°cos8°/cos15°cos8°
=sin15°/cos15°
=sin(45°-30°...

全部展开

原式=[sin(15°-8°)+cos15°sin8°]/[cos(15°-8°)+sin15°sin8°]
=(sin15°cos8°-cos15°sin8°+cos15°sin8°)/(cos15°cos8°-sin15°sin8°+sin15°sin8°]
=sin15°cos8°/cos15°cos8°
=sin15°/cos15°
=sin(45°-30°)/cos(45°-30°)
=(sin45°cos30°-cos45°sin30°)/(cos45°cos30°+sin45°sin30°)
=(√6/4-√2/4)/(√6/4+√2/4)
=2-√3

收起