风空调5.2.6：消声器、

已知 A(1,2,0)，B(3,0,-3)，C(5.2.6)，[img=56x19]1803564db2a6155.png[/img]的面积为 A: 28 B: 14 C: 9 D: 13

（视频5.2.6测试题）http://image.zhihuishu.com/download/upload/uccmanage/eweb/user/20150724091753721.png" _ewebeditor_pa_src="http%3A%2F%2Fimage.zhihuishu.com%2Fdownload%2Fupload%2Fuccmanage%2Feweb%2Fuser%2F20150724091753721.png" border="0