1. If a graph is folded in half along a straight line, the graphs on both sides can completely overlap. This figure is an axisymmetric figure, and the straight line where the crease is located is called the axis of symmetry.

2. The parts on both sides of the symmetry axis can completely overlap if they are the same in shape, size, position and direction.

3. Draw the symmetry axis with a dotted line.

4. Rectangular, square and circle are symmetrical figures.

A rectangle has two axes of symmetry. A square has four axes of symmetry. A circle has countless axes of symmetry.

Second, mirror symmetry.

Like that lake. Reflection and looking in the mirror are mirror images. The reflection of the lake is symmetrical with respect to the horizontal plane, while looking in the mirror is symmetrical with respect to the vertical plane. When looking in the mirror, the up and down, front and back positions of people inside and outside the mirror will not change, but the left and right positions will be reversed.

Third, add symmetrical graphics.

When drawing the other half of a symmetrical figure, you can first find the symmetrical points of the two ends of each line segment in the grid, and then connect them with straight lines. The symmetry point of a point on the axis of symmetry is still this point. The symmetry axis is vertical, and the figure is symmetrical left and right; The symmetry axis is horizontal, and the figure is symmetrical up and down.