DC=AC=CB∠CBE=∠CDE=（180-90-60）/2 = 15度cos∠CBE=(根号2+根号6)/4BC=根号2CE=BC*tan15AE = AC-CE=BC-BC*tan15 = 根号2*（1-（2-根号3））=根号2*（根号3-1）=根号6-根号2
