史坦纳定理[1]是几何中的有名定理,其内容是:设△ABC的垂心为H,其外接圆上的任一点为P,△ABC关于点P的西摩松线通过线段PH的中点.史坦纳定理的推论是:△ABC外接圆上的一点P的关于边BC、CA、AB的对称点和△ABC的垂心H在同一条直线上,该直线叫△ABC关于点P的镜像线.安宁定理也可以看作史坦纳定理的推论,其内容是:在一个圆周上取四 Steiner’s theorem [1] is a well-known theorem in geometry. The content is: Suppose the center of gravity of △ ABC is H, and any point on the circumcircle is P, △ ABC is about the Seymour line of point P passing through line segment PH Median Steinage’s reasoning is: △ ABC circumcircle of a point P on the side BC, CA, AB symmetry point and Δ ABC vertical centimeter H in the same line, the line called △ ABC point P The tranquility theorem can also be regarded as a corollary of Steiner’s theorem, which reads: Take four