例1.已知Z、n求:lan、lamn 圆心 解: H ah 搭桥 H 2 H H i1=?a c H b nb = 0 搭桥 ● i aH = H ab 1− i =   =1− (− ) a c c b z z z z i ac = aH Hc i i = −   − − = c b a c c b z z z z z z 1 1 ( ) H cb H ab i i − − = 1 1 cH H ab i i 1 = (1− ) = = aH a H i n n = = ac a c i n n 例 1. 已知 Z、na 求: iaH 、iac、nH、nc 解: 3 1 2 2 ’ H 4 i14= ？