Method 2: On the plane, if there is a straight line, all the points in Figure F are graphs composed of symmetrical points about the straight line. If it is still the figure F itself, it is called an axisymmetric figure, and the straight line has its own axis of symmetry.
Several common axisymmetric and centrosymmetric figures;
Axisymmetric graphics: line segment, angle, isosceles triangle, equilateral triangle, diamond, rectangle, square, isosceles trapezoid, circle, hyperbola (with two symmetry axes), ellipse (with two symmetry axes), parabola (with one symmetry axis), etc.
Number of symmetry axes: an angle has a symmetry axis, that is, the angle bisector of the angle; The isosceles triangle has an axis of symmetry, which is the median vertical line of the base; An equilateral triangle has three axes of symmetry, that is, the median vertical lines on three sides; A diamond has two symmetry axes, which are straight lines where two diagonals are located, and a rectangle has two symmetry axes, which are straight lines between two groups of opposite sides.