圖片參考:
http://imgcld.yimg.com/8/n/HA00936359/o/701108120063213873441740.jpg
For any ∆ABC (Beside isos. ∆),
AJ is an angle bisector of ∆BAC, so ∠BAJ=∠CAJ.
HK is a perpendicular bisector of BC, so HK⊥BC,BK=CK.
Extend AJ and HK, they meet at point O.
Prove that point O is outside the ∆ABC (Beside isos. ∆).