1, after two straight lines intersect, there is only one common vertex and both sides of two corners are opposite extension lines. Such two angles are called antipodal angles.

2. The ray drawn from the vertex of an angle divides the angle into two equal angles. This ray is called the bisector of this angle.

3. When doing the problem, if you want to draw an angle, you must have a small symbol indicating the angle after drawing, that is, the right angle is a straight small broken line, and the obtuse angle and acute angle are small arcs. Whether to mark vertices and edges depends on the specific requirements of the problem.

4. Complementarity and complementarity refer to the quantitative relationship between two angles, which has nothing to do with the position of the two angles, while adjacency requires the two angles to have a special positional relationship. 5. The drawing method of corners is to draw a line, two corners, three lines and four labels. The angle a pair of triangles can draw is a multiple of 15.