第34页 - 亮点给力提优课时作业本九年级数学江苏版

C

D

$6\sqrt{3}$

$2\sqrt{5}$或$4\sqrt{5}$

解: 因为$\angle ACB = 90^{\circ}，$$\angle A = 40^{\circ}，$所以$\angle B = 90^{\circ}-\angle A = 50^{\circ}。$因为$CB = CD，$所以$\angle CDB = \angle B = 50^{\circ}，$所以$\angle ACD = \angle CDB-\angle A = 10^{\circ}。$

A

B

C