cos15°/sin15°=2+根号3 为什么?

问题描述:

cos15°/sin15°=2+根号3 为什么?

cos15°/sin15°
=sin75°/cos75°
=tan75°
=tan(45°+30°)
=(tan45°+tan30°)/(1-tan45°tan30°)
=(1+√3/3)/(1-√3/3)
=(3+√3)/(3-√3)
=2+√3