2.？ The point on the bisector of an angle is equal to the distance on both sides of the angle.
3.？ A line segment is an axisymmetric figure whose axis of symmetry is perpendicular to the line segment and divides it into two parts. Such a straight line is called the midline of this line segment.
4.？ The point on the vertical line of a line segment is equal to the distance between the two endpoints of the line segment.
5.？ A triangle with two equal sides is called an isosceles triangle.
6.？ The bisector of the top angle, the median line on the bottom and the high coincidence on the bottom of an isosceles triangle (also called "three lines in one") are the symmetry axes of the isosceles triangle.
7.？ A triangle with three equilateral sides is an equilateral triangle, also called a regular triangle.