tan15度等于多少
tan15°
=tan(60°-45°)
=(tan60°-tan45°)/(1+tan60°*tan45°)
=(根号3-1)/(1+根号3)
=(根号3-1)*(根号3-1)/[(根号3+1)(根号3-1)]
=(4-2根号3)/2
=2-根号3