图文参考：∵AB⊥平面BCD∴∠ACB就是AC和平面a所成的角作AE⊥CD,垂足为E,连接BE∵AB⊥平面BCD∴AB⊥CD ∵AE⊥CD∴BE⊥CD ∵△ACE中,AEC = 90°,ACD = 60°设CE = x,∴AC = 2x∵△BCE中,BCD = 45°,BEC = 90°,CE = x...