"Determination of Congruent Triangles" PPT Courseware 5

Description

"Determination of Congruent Triangles" PPT Courseware 5

teaching objectives

In the teaching of this lesson, students are not only required to learn how to identify congruent triangles such as "sides, angles, and sides," but more importantly, students are required to master the methods of researching problems and initially understand the mathematical ideas of classification discussions, thereby stimulating students. Interest in learning mathematics. To this end, I established the following:

1. Knowledge goals:

(1) Students, under the guidance of teachers, actively and actively experience the process of exploring the conditions for congruence of triangles, and experience the process of obtaining mathematical conclusions through operations and induction.

(2) Master the method of determining the "angles and sides" of congruent triangles, and be able to use the congruence of triangles to solve some practical problems.

2. Process and methods: Experience the process of exploring the congruence conditions of triangles, understand the methods of analyzing problems, and accumulate experience in mathematical activities.

3. Emotions and attitudes: Through the acquisition and use of "corner and corner axioms", students' rigorous logical thinking qualities and the spirit of courage to explore, unity and cooperation are cultivated.

2.Key points and difficulties

Teaching focus: the content and application of "Axiom of Edge, Corner and Edge".

Teaching difficulties: discover, verify and summarize the content of edge and edge axioms, and use this conclusion to solve practical problems.

(1) Create situations and introduce new knowledge

1. Introduced by life problems

The triangular glass decoration on Xiao Ming's wardrobe was broken. His mother asked Xiao Ming to go to the glass shop to get a piece. Could you please tell Xiao Ming what to do?

2.Draw a picture

Use a scale and compass to draw a ΔABC such that AB=10cm, BC=8cm, and ∠C=45°.

In this link, students can be divided into groups and draw pictures to compare and "give counterexamples" to conclude that two triangles cannot be congruent at all times. Therefore, further guide students to see whether the situation changes if the angle between the two sides AB and BC of the triangle is ∠B=45°.

(2) Operational communication and initial conclusions obtained

1. do it

Given △ABC, let AB=10cm, AC=8cm, ∠DAB=45°, and draw this triangle.

step:

1. Draw line segment AB=10cm;

2. Draw ∠DAB=45°;

3. Intercept AC=8cm on ray AD; connect BC.

△ABC is what you want.

How to determine if triangles are congruent:

Two triangles are congruent if both sides and their included angles are equal (can be abbreviated as "side-angle-side" or "SAS")

Geometry language:

In △ABC and △DEF,

AB=DE

∠B=∠E

BE=CF

∴ △ABC≌△DEF (SAS)

Tip: The corresponding vertices should be written in the corresponding positions

(4) Class summary

1. Side-Angle-Side Axiom: Two triangles are congruent if two sides and their ______ correspond to equal values ​​(SAS)

2. The mathematical methods used in the process of discovering the corner-side axiom (including drawing, experiment, conjecture, analysis, induction, etc.)

3. Mathematical methods used in the application of the side-angle-side axiom:

Prove that line segments (or angles) are congruent--Prove that the two triangles in which the line segments (or angles) are located are congruent.

Tip: Make full use of the implicit conditions in graphics, such as common edges, common angles, opposite vertex angles, etc.

(5) Assign homework

(1) Must do: Textbook P43 Exercises Group A 1, 2, 3

(2) Optional: Textbook P43 Exercises Group B 1 and 2

As a designer, embellish congruent triangles into life.

(3) Know the knowledge in the next section:

Preview the contents of textbook P45~46.

Through homework, the continuation of the class and the formation of skills are achieved.

Keywords: teaching courseware on the judgment of congruent triangles, download the eighth grade mathematics PPT courseware of the Hebei Education Edition, eighth grade mathematics slide courseware download, download the PPT courseware on the judgment of congruent triangles, .PPT format;

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Update Time: 2024-11-18

This template belongs to Mathematics courseware Hebei Education Edition Eighth Grade Mathematics Volume 1 industry PPT template

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