关于三角形的一些概念边、角、角平分线、中线、高三角形三边的关系三角形的内角和三角形的分类三角形的外角按边分类按角分类全等三角形一般三角形全等性质直角三角形全等判定三角形的稳定性角平分线的性质与判定尺规作图基本作图性质判定特殊三角形等腰三角形直角三角形等边 About some concepts of triangles Edges, angles, angles, bisectors, midlines, and high triangles Relationships of three sides of triangles Internal angles of triangles and triangles Classification of triangles Edges by edge Classification by angle Congruent triangles General triangles Congruent nature Right triangles Congruent judgment The stability of the bisector of the triangle and the nature of the decision ruler to determine the basic drawing nature of the special triangular isosceles triangle right angle triangle equilateral