"Sum of Interior Angles Theorem of a Triangle" Proof of Parallel Lines PPT (Lesson 1)

Description

"The Sum of the Angles of a Triangle Theorem" Proof of Parallel Lines PPT (Lesson 1), 29 pages in total.

Part One: Learning Objectives

1. Be able to use the properties of parallel lines and the definition of straight angles to prove that the sum of the interior angles of a triangle is equal to 180°. (Key points)

2. Be able to use the triangle interior angle sum theorem to calculate. (Difficulty)

Sum of interior angles theorem of a triangle PPT, part 2 content: teaching a new lesson

Proof of the sum of interior angles theorem of a triangle

Explore: Draw a random triangle on the paper, cut out its inner corners and put them together.

Key points

as auxiliary line

Here, for the purpose of proof, the lines added to the original figure are called auxiliary lines. In plane geometry, auxiliary lines are usually drawn as dotted lines.

Summary of ideas

In order to prove that the sum of three angles is 180°, convert it into a straight angle or complementary interior angles on the same side, etc. This conversion idea is a common method in mathematics.

Sum of interior angles theorem of triangles PPT, part 3: practice in class

1. Find the x value in each of the following figures.

2. As shown in the figure, then ∠1+∠2+∠3+∠4=___________.

3. As shown in the figure, in the quadrilateral ABCD, point E is on BC, ∠A+∠ADE=180°, ∠B=78°, ∠C=60°, find the degree of ∠EDC.

Sum of interior angles theorem of triangles PPT, Part 4 content: Class summary

prove

Learn how to add guide lines and their purpose

content

The sum of the interior angles of a triangle is 180°

Keywords: Free download of Beijing Normal University edition eighth-grade mathematics PPT courseware for the first volume, PPT download of the sum of interior angles theorem of a triangle, PPT download of the proof of parallel lines, .PPT format;

For more information about the PPT courseware "Proof of Parallel Lines and the Sum of Interior Angle Theorem of Triangles", please click on the Proof of Parallel Lines PPT Theorem of Sum of Interior Angle of Triangles PPT tag.

"Sum of Interior Angles Theorem of a Triangle" Proof of Parallel Lines PPT Download:

"Sum of Interior Angles Theorem of a Triangle" Proof of Parallel Lines PPT download, 12 pages in total. Part 1: Basic knowledge points Knowledge point 1 The sum of the interior angles of a triangle theorem 1. In △ABC, A=B+C, then the correct judgment of the shape of △ABC is (A) A. Right triangle B. Acute...

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"Sum of Interior Angles Theorem of a Triangle" Proof of Parallel Lines PPT Courseware (Lesson 1):

"Sum of Interior Angles Theorem of a Triangle" Proof of Parallel Lines PPT Courseware (Lesson 1), 21 pages in total. Part 1 content: Learning objectives: Properties and applications of the sum of the interior angles of a triangle. The relationship between the two acute angles of a right triangle... ... The sum of the interior angles of a triangle PPT, Part 2..

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Update Time: 2024-09-29

This template belongs to Mathematics courseware Beijing Normal University Edition Eighth Grade Mathematics Volume 1 industry PPT template

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