回複:如果我告訴大家,上述答案中有且僅有一個是正確的,是哪個呢?:)
Draw a circumcircle of triangle ABC with the circumcenter O. Obvious, O is on the line of the perpendicular bisector of BC, which passes the circumcircle at O'. Connect AO'. Since arc BO'=arc CO', angle BAO'= angle O'AC.
Therefore, the meet point of angle bisector of angle BAC and the perpendicular bisector of BC can't be inside of triangle ABC.