等腰三角形是一种特殊三角形，由它的定义、性质和判定可知，等腰三角形有三大功能：（１）利用等腰三角形可以证明两条线段相等（等腰三角形的两腰相等、等腰三角形顶角的平分线平分底边、等腰三角形底边上的高平分底边）；（２）利用等腰三角形可以证明两角相等（等腰三角形 An isosceles triangle is a special kind of triangle. It is known by its definition, nature, and judgment that isosceles triangles have three major functions: (1) The use of isosceles triangles can prove that two line segments are equal (the isosceles triangles have equal waist and isosceles. The bisector at the top of the triangle bisects the bottom and the high bisector at the bottom of the isosceles triangle); (2) The isosceles triangle can be used to prove that the two angles are equal (isometric triangles)