Do the radius OC chord BC. Then the central angle ∠ AOC = 2 ∠ Cob (△ outer angle is equal to the sum of non-adjacent inner angles, replaced by the same amount),

∠AOC= 120？ ，∠COB=60？ ;

∠CAB=30？ (The circumferential angle on the same arc is equal to half the central angle),

∠CBA=60？ ，∠ACB =90？ The circumferential angle on the diameter is a right angle.

And ∠ CDB = 3 ∠ cab = 90? . ∠BCD =30？ .

BC = 8 (right angle △ right angle side is equal to half of hypotenuse) = OB (△ OCD is equal to side, and the inner angle is 60? ),

AB= 16 .

∵∠ACD∠BCD = 60？ ∶30? = 2:1,so AD = 16×? .

∴△CAD area = AD CD=? × 16×? ×6=32。