The related properties of circle are widely used in industrial and agricultural production, transportation and other aspects, involving a wide range of mathematical knowledge; Learning this chapter well can improve the comprehensive ability to solve problems. The content of this section, the position relationship between tight joint and circle, embodies the viewpoint of motion, which is the basis of learning related properties, and also paves the way for learning the position relationship between circle and circle and continuing to learn geometry knowledge in senior high school.

I. Knowledge objectives

Let the students know and understand the three positional relationships between straight lines and circles from specific examples, and summarize their definitions. They will use definitions to judge the positional relationship between straight lines and circles, and explore the quantitative relationship between straight lines and circles and its application through analogy, observation and experiment with the positional relationship between points and circles.

Second, the process and methods

Through observation, experiment, discussion, cooperative research and other mathematical activities, let students understand the general methods of exploring problems; It is observed that the distance between the center of the circle and the straight line and the quantitative relationship between the radius of the circle are equivalent to the positional relationship between the straight line and the circle, thus realizing the transformation of the positional relationship and the quantitative relationship, and infiltrating the mathematical thought of movement and transformation.

Third, emotional attitudes and values

Create question scenes to stimulate students' curiosity; Experience the exploration and creation in mathematics activities, feel the rigor of mathematics and the correctness of mathematical conclusions, and gain a successful experience in learning activities; Through the application of transformation mathematics thought, students can realize that things are dialectical materialism thought of universal connection and mutual transformation.

Fourthly, the importance and difficulty of teaching.

1. Key point: Understand the three positional relationships of intersection, separation and tangency between a straight line and a circle.

2. Difficulties: Students can reveal the positional relationship between the straight line and the circle according to the quantitative relationship between the distance D from the center of the circle and the radius R of the circle; Three methods are used to judge the positional relationship between a straight line and a circle.

Verb (abbreviation of verb) abstract

Cultivate students' generalization ability through students' generalization definition. From the nature and judgment of the position relationship between point and circle to the position relationship between straight line and circle, it is easier for students to think of experimental methods such as drawing and mapping, communicate and cooperate in groups, and teachers give timely guidance to explore the quantitative relationship between the distance from the center of the circle to the straight line and the radius of the circle.