Question

在平面直角坐标系中A(-3,4)B(-1,2)O为原点，如图所示，求角形AOB的面积

Answer 1

过A作AC垂直于Y轴，垂足C在Y轴上；过B作BD垂直于Y轴，垂足D在Y轴上；
CO=4，AC=3，BD=1，CO=4，DO=2;
S△AOB=S△AOC-S直角梯形ABDC-S△BOD
=CO*AC/2-(BD+AC)*(CO-DO)/2-DO*BD/2
=4*3/2-(1+3)*(4-2)/2-2*1/2
=6-4-1
=1