笔者在进行圆锥曲线章节内容的教学时,发现圆锥曲线的一个性质:图1定理过圆锥曲线焦点弦的一个端点向相应的准线作垂线,垂足与另一个端点的连线必经过焦点到相应准线的垂线段的中点.如图1:AB为经过焦点F的焦点弦,l为相应的准线,过B作l的垂线,垂足为C,连AC,证明:AC经过FK的中点N When I was teaching conic sections, I found a property of the conic: Figure 1 Theorem One point of the conic focus chord is perpendicular to the corresponding line, and the connection between the foot and the other endpoint must be in focus To the midpoint of the vertical line of the corresponding line as shown in Figure 1: AB for the focal point through the focus F string, l for the corresponding line, B for l vertical line, foot drop C, with AC, prove: AC After the midpoint of FK N