(1)(2)出A2、B2、C2的坐标分别是:(0,-2),(3,-2),(3,0);(3)作AD⊥x轴,延长CB交y轴于点E.则S梯形ADEC= 1 2 (AD+CE)?DE= 1 2 (1+3)×3=6,S△ECA2= 1 2 ?EC?EA2= 1 2 ×3×3=4.5,S△ADA2= 1 2 AD?D2= 1 2 ×1×6=3,则S△ACA2=S梯形ADEC+S△ECA2-S△ADA2=6+4.5-3=7.5.