基础练习
1.4
2.4 ,9
3.30°,1 : 2
4.证 △AOB ≌ △COD 或
证 OB = 1/2BD = 1/2AC = OC
综合运用
5.由EF = EC,∠AEF = ∠DCE ,∠A = ∠D = Rt∠,
得△AFE∽△DEC
6.(1)30°
(2)证 △DEF ≌ △BCF,或先证DF = BF
*7.由 BE = BO,得∠OBE = 30°,∠ABO = 60°,
得 AB = BO = BE.
∴ ∠BAE = 45°,∠CAE = 15°