(sina5π/12+cos5π/12)(sin5π/12-cos5π/12)

分类: 作业答案 • 2021-12-28 16:06:19

问题描述：

答

（sin5π/12+cos5π/12)(sin5π/12-cos5π/12)=sin²5π/12-cos²5π/12
=(1-cos5π/6)/2-(1+cos5π/6)/2
=(1+√3/2)/2-(1-√ 3/2)/2
=√3/2