∴AC⊥BD,AD=AB,∠DAC=∠BAC=∠ACD=30

Then ∠ DAB = ∠ DAC+∠ BAC = 30+30 = 60

AD = AB，∠DAB=60

△ Abd is an equilateral triangle.

(2)∫OD = OB = 1/2BD = 1

∠AOD=∠AOB=90 (AC⊥BD)

∴AD=2OD=2, then OA=√3.

∴AC=2OA=2√3