As the saying goes, "everything is difficult at the beginning." If you want to have a good math class, a good beginning is half the battle.

First, the new introduction method of warm and solid knowledge

The new teaching method can organically combine the old and new knowledge, so that students can naturally acquire new knowledge from the review of the old knowledge. For example, when talking about the cutting theorem, first review the content and proof of the chord intersection theorem, that is, the product of the length of two straight lines divided by the intersection point in the "circle" is equal. When two chords are moved so that their intersection points are outside the circle, there are three situations. In this way, students can easily understand the secant theorem and the mathematical expressions of inference, and on this basis, guide students to describe the contents of the theorem, and sum up that the similarity of the circular power theorem is that the products of line segments are equal. The difference is that the intersection chord theorem is the inner segment of the intersection point, while the secant theorem infers that both ends of the outer segment coincide with the tangent theorem. Import like this,

Students can find a string of new knowledge from the review of old knowledge and master the proof method of line segment product equality. Second, the analogy introduction method