范子坚老师在本刊1994·5期《谈抛物线与x轴的两个交点和顶点连线构成的三角形》一文,对抛物线的顶点和它与x轴的两个交点的连线构成的等腰三角形介绍了与△=b~2-4ac有关的三个计算公式。(见该文)本文再给出此等腰三角形的腰长、顶角、底角的计算公式以作补充,有趣的是这些公式也都与△有关。 Teacher Fan Zijian’s paper on the triangle formed by the two intersections and vertices of the parabola and the x-axis in the 1994·5 issue of this paper describes the isosceles triangle formed by the connection between the vertices of the parabola and its two intersections with the x-axis. Three calculation formulae related to △=b~2-4ac are introduced. (See the article.) This paper also gives the calculation formulas for the waist length, apex angle, and base angle of this isosceles triangle. It is interesting to note that these formulas are all related to △.