math_

　　The high, middle, and Angle bisector of the triangle is the main line, in the triangle and triangle on the Angle of inside and outside. Teaching experiments for students to understand the stability of the triangle, in know the inside of the triangle and is equal to 180 °, on the basis of reasoning, which outside, the nature of the triangle are obtained. By promoting the related concept of the triangle, then introduces the related concepts of polygon, some properties of triangle was used to study the inside and outside and the formula of polygon. These knowledge to deepen the students understanding of triangle, is not only the foundation of learning special triangle, is also the foundation of studying other graphics. Finally combining with case study the relevant problems of Mosaic, embodies the polygon angles and formula application in real life.

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