sinπ/12-sin5π/12+2sinπ/8sin3π/8
问题描述：
sinπ/12-sin5π/12+2sinπ/8sin3π/8
答
化成sin(15度)-sin(75度)+2sin(22.5度)sin(67.5度)答案为0 步骤如下：sin(15度)=sin(45度-30度)=(√6-√2)/4sin(75度)=sin(45度+20度)=(√6+√2)/4因为sin(22.5度)=sin(90度-67.5度)=cos(67.5度)所以2sin(22.5度)sin...