贵刊1999年第1期刊有陈善珍老师的文章《双曲线的定义的一错误应用》。指出如下结论: 双曲线x~2/a~2-y~2/b~2=1(a>0,b>0)的过焦点F_1的弦AB长为m,另一焦点为F_2,则A、B两点在双曲线的同一支上时,△F_2AB的周长为4a+2m,而当A、B两点在双曲线的两支上时不为4A+2m。那么,当A、B在双曲线的两支时,△F_1AB In your first issue of the 1999 issue of Journal of You, Mr. Chen Shanzhen’s article “A Wrong Use of Hyperbolic Definitions”. The following conclusions are pointed out: The chord AB of the hyperfocal F_1 with the hyperbolas x~2/a~2-y~2/b~2=1(a>0, b>0) is m and the other focal point is F_2. When A and B are on the same branch of hyperbola, the perimeter of △F_2AB is 4a+2m, and when A and B are on two branches of hyperbola, it is not 4A+2m. Then, when A and B are in two hyperbolic curves, △F_1AB