Problem-solving skills of auxiliary lines of mathematics and geometry in the second day of junior high school: if there is an angle bisector in the figure, the two sides can be vertical, and then the idea can be developed by using the properties of the angle bisector; If there are bisectors and parallel lines in the graph, consider constructing an isosceles triangle. The most classic application is the classic question method in which the sum of two line segments is equal to the third line segment. When the bisector and vertical line of the angle appear, we consider using the three lines of the isosceles triangle to get the conditions we need and the idea of solving problems quickly.

Problem-solving skills of mathematical geometry auxiliary line in senior two.

First, if there is an angular bisector in the graph, it can be perpendicular to both sides, and then the idea can be expanded by using the properties of the angular bisector. Of course, graphics can also be folded in half, and the relationship between line segments or the corresponding relationship between angles can be obtained by using symmetry.

Secondly, if there are bisectors and parallel lines in the graph, we can consider constructing isosceles triangles. The most classic application is the classic question method in which the sum of two line segments is equal to the third line segment.

Thirdly, when the bisector and vertical line of the angle appear, we consider using the three lines of the isosceles triangle to get the conditions we need and the idea of solving problems quickly. This method of changing conditions can open the dilemma that everyone has no idea.

Fourthly, when there is a vertical line in the condition, we usually connect the two ends. The condition is extended by using the properties of the median vertical line.

Fifth, when proving the multiple relationship and half relationship of line segments, we can make auxiliary lines by extending or shortening the length of line segments.

Sixth, when a triangle appears in the graph for two hours, connecting two midpoints, we can consider using the midline of the triangle as an auxiliary line.

Seventh, when a triangle has a median line, if there is no way to solve the conditions in the analysis process, we can consider extending the median line and proving the congruence of the triangle with the median line, which can improve everyone's learning efficiency and expand their thinking.

The number of auxiliary lines in junior high school mathematics is not as large as possible. Many students have a wrong cognition when they first come into contact with such auxiliary lines. They always think that drawing more auxiliary lines will make the analysis of geometric figures more thorough and clear. This is a very wrong cognition. So what are the methods of auxiliary lines in junior high school mathematics? Today, I will bring you the method of junior high school mathematics auxiliary line.

Methods 1: The midline of triangle is always double. Questions with a midpoint, usually the center line of a triangle. By this method, the conclusion to be proved is properly transferred, and the problem is easily solved.

Method 2: When there is a bisector, we often take the angular bisector as the symmetry axis, use the properties of the angular bisector and the conditions in the problem to construct a congruent triangles, and use congruent triangles's knowledge to solve the problem.

Method 3: The conclusion is that when two line segments are equal, auxiliary lines are often drawn to form congruent triangles, or some theorems about bisecting line segments are used.

Method 4: The conclusion is that the sum of one line segment and another line segment is equal to the third line segment, and truncation method or complement method is often used. The so-called truncation method is to divide the third line segment into two parts and prove that one part is equal to the first line segment and the other part is equal to the second line segment.