10 × sin45° ÷ sin75° 怎么算
问题描述：
10 × sin45° ÷ sin75° 怎么算
答
sin75
=sin(30+15)
=sin30cos15+cos30sin15
=(√6+√2)/4
原式=10×√2/2÷[(√6+√2)/4]
=5√2×4/(√6+√2)
==5√2(√6-√2)
=10√3-10