1、AD是上底,BC是下底时
△ABO和△ADO在BD上等高
∴S△ABO/S△ADO=OB/OD=4/6=2/3
即OB/OD=2/3
∵AD∥BC
∴△ADO∽△BCO
∴S△BCO/S△ADO=(OB/OD)²=(2/3)8=4/9
即S△BCO=4/9S△ADO=4/9×6=8/3
∵S△ABO=S△CDO
∴S梯形ABCD
=S△AOB+S△ADO+S△BCO+S△CDO
=4+6+8/3+4
=14+8/3
=50/3平方厘米
2、AB是下底,DC是上底
△ABO和△ADO在BD上等高
∴S△ABO/S△ADO=OB/OD=4/6=2/3
即OB/OD=2/3
∵AB∥DC
∴△ABO∽△DCO
∴S△ABO/S△DCO=(OB/OD)²=(2/3)²=4/9
∴S△DCO=9/4S△ABO=9/4×4=9
∵S△ADO=S△BCO=6
∴S梯形ABCD
=S△AOB+S△ADO+S△BCO+S△CDO
=4+6+9+6
=25平方厘米简单点行吗