The specific introduction of the perimeter:

The length integral of the edge around a finite area is called the perimeter, which is the length of a graph. The perimeter of a polygon is also equal to the sum of all the edges of the graph.

The length integral of the edge around a finite area is called the perimeter, which is the length of a graph. The circumference is represented by the letter c, the circumference of a circle =πd=2πrd is the diameter, r is the radius π, and the circumference of a sector =2R+nπR÷ 180? N= center of the circle =2R+kR, and k= radian.

Related teaching:

The understanding of perimeter is the learning content of the third grade in the first phase of compulsory education mathematics (Volume I). The learning content of "understanding of perimeter" in the curriculum standard actually includes three levels: first, let students know the concept of perimeter and experience it in real life; Secondly, let students master the method and process of measuring circumference; Finally, experience and feel the application of mathematics in life.

For the specific course content of "Cognition of Perimeter", the course standard clearly points out the target requirements in the content standard, that is, point out and measure the perimeter of specific figures, and explore and master the perimeter formulas of rectangles and squares.

In addition, in the overall goal of mathematics curriculum, "get some preliminary practical experience in mathematics and be able to use the knowledge and methods learned to solve simple problems."

Feeling the role of mathematics in daily life "is also the goal requirement of" knowing the perimeter ". The course goal here is actually the refinement and concrete embodiment of knowledge and skills, mathematical thinking, problem solving, emotion and attitude goals, which involves the following requirements in the first stage: "the skill of obtaining preliminary measurement (including estimation)" in the knowledge and skills goal.

The goal of mathematical thinking is to "develop the concept of space in the process of exploring the shape, size, positional relationship and movement of simple objects and figures"; On the goal of solving the problem, "there are different solutions to understand the same problem." Experience in solving problems with peers.

Initially learn to express the general process and results of solving problems "; As well as the goal of emotion and attitude, "with the encouragement and help of others, I am curious about things related to mathematics around me and can actively participate in vivid and intuitive mathematics activities. "

Feel the close connection between mathematics and daily life. Rationality of mathematical thinking processes such as observation, operation and induction. Under the guidance of others, mistakes in mathematical activities can be found and corrected in time. "