圖片參考:http://i41.photobucket.com/albums/e288/s0malia_0v0/97443612-1.jpg?t=1234176629
不明白怎樣證明!!是關於中線定理及截線定理的!
更新1:
http://i41.photobucket.com/albums/e288/s0malia_0v0/97443612-1.jpg?t=1234176629 如看不清楚-__-請click上面既網址!