"Sum of the Interior Angles of a Triangle" PPT courseware for understanding triangles and quadrilaterals

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"Sum of the Interior Angles of a Triangle" PPT courseware for understanding triangles and quadrilaterals

The meaning of the sum of the interior angles of a triangle:

The angle formed by two adjacent sides of a triangle is called the interior angle of the triangle. Every triangle has three interior angles.

Tear off the three corners of the triangle and put them together again, and find that ∠1, ∠2, and ∠3 exactly form a right angle, that is, ∠1＋∠2＋∠3=180°. It follows that the sum of the interior angles of a triangle is 180°.

Fold ∠1 downward. When folding, pay attention to parallel folding so that the vertex of ∠1 falls on its opposite side. Then fold ∠2 and ∠3 so that the vertices of ∠2 and ∠3 coincide with the vertex of ∠1. It is found that ∠1, ∠2, and ∠3 exactly form a right angle, that is, ∠1＋∠2＋∠3=180°. From this, it can be concluded that the sum of the interior angles of the triangle is 180°.

Are the following statements correct?

The sum of the interior angles of the large triangle is greater than the sum of the interior angles of the small triangle.

There can be at most one right angle in a triangle.

Divide a triangle into two triangles. The sum of the interior angles of each small triangle is ( ) degrees.

Divide a rectangle into two triangles. The sum of the interior angles of each small triangle is ( ) degrees.

Let’s review, what did we learn in this lesson?

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"Sum of Interior Angle Theorem of a Triangle" PPT courseware 2:

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"Sum of Interior Angles Theorem of a Triangle" PPT courseware:

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Update Time: 2024-09-28

This template belongs to Mathematics courseware Mathematics Volume 2 for Grade 4 of Beijing Normal University industry PPT template

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