✔ 最佳答案
ΔDEF~ΔKML
ML / EF = KM / DE ( 相似Δ對應邊 )
ML / 7 = 9 / 3
ML / 7 = 3
ML = 21
FD / LK = DE / KM ( 相似Δ對應邊 )
FD / 33 = 3 / 9
9( FD ) = 3( 33 )
9( FD ) = 99
FD = 11 //
2007-04-12 23:09:54 補充:
我畫了一個圖, 你會更易明白
http://i178.photobucket.com/albums/w276/calligraphy-yahoo2006/ScreenHunter_02Apr-2.jpg