sin6+cos15*sin9/cos6-sin15*sin9
问题描述：
sin6+cos15*sin9/cos6-sin15*sin9
数字上面有度数
答
(sin6+cos15*sin9)/(cos6-sin15*sin9)=[sin(15-9)+cos15*sin9]/[cos(15-9)-sin15sin9]=(sin15cos9-cos15sin9+cos15sin9)/(cos15cos9+sin15sin9-sin15sin9)=(sin15cos9)/(cos15cos9)=sin15/cos15=tan15=(1-cos30)/sin...