求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
问题描述：
求cos8°-sin7°×sin15°分之sin8°+sin7°cos15°的值
答
(sin(15-7)+sin7cos15)/(cos(15-7)-sin7sin15)=(sin(15)cos(7)-cos(15)sin(7)+)+sin7cos15))/cos(15)cos(7)+sin(15)sin(7)-sin7sin15)=sin(15)cos(7)/cos(15)cos(7)=tan(15)＝tan(45-30)=(tan45-tan30)/(1+tan45*tan...