Question

求值（sin7°+cos15°sin8°）/（cos7°-sin15°sin8°）

求值（sin7°+cos15°sin8°）/（cos7°-sin15°sin8°）

Answer 1

=(sin(15-8)+cos15sin8)/(cos(15-8)-sin15sin8
=(sin15cos8-cos15sin8+cos15sin8)/(cos15sin8+sin15cos8-sin15sin8)=sin15/cos15
=tan15
=tan(45-30)
=2-根3

Answer 2

=(sin(15-8)+cos15sin8)/(cos(15-8)-sin15sin8
=(sin15cos8-cos15sin8+cos15sin8)/(cos15sin8+sin15cos8-sin15sin8)=sin15/cos15
=tan15
=tan(45-30)
=2-根3
额。上面忘登陆了。