"Isosceles Triangle" PPT Courseware 4

Description

"Isosceles Triangle" PPT Courseware 4

Curriculum standard requirements

Explore and prove the properties of isosceles triangles:

The two base angles of an isosceles triangle are equal;

The high line, middle line and vertex bisector on the bottom edge coincide (three lines merge into one).

Explore and master the determination theorem of isosceles triangles:

A triangle with two equal angles is an isosceles triangle

Goal-oriented: Through problem feedback, existing problems can be further clarified and targeted.

Issues reflected:

1. The writing method of corresponding vertices is not standardized, and the writing of corresponding elements is not comprehensive;

2. Incomplete consideration of the problem (Example 2)

3. The angle representation method is not standardized.

learning target

1. Understand the properties of isosceles triangles, master the determination methods of isosceles triangles, and be able to use them to solve related problems;

2. Through independent thinking and cooperative exploration, learn how to use a ruler and compass to construct an isosceles triangle;

3. Be passionate and go all out to develop the good qualities of courage to explore and rigorous reasoning.

Discussion and exploration (8 minutes)

1. Questions and errors encountered during preview or tutorial:

Explore and prove the properties and judgments of isosceles triangles and use a ruler and compass to construct isosceles triangles

2. Key discussion: Preview and self-study Example 1 Example 2

Goals achieved:

A layer solves all questions, implements the guidance plan, summarizes and expands;

Level B has solved all the questions in the study plan and corrected them with red pen in time.

Level C learns the key points in the guidance plan and implements them well

3.Requirements:

1. Keep asking questions around the goal and answer questions based on the topic;

2. Speak actively and express your thoughts bravely;

3. Summarize problem-solving ideas and methods, pick up the red pen and correct mistakes in time.

4. Under the overall control of the group leader.

Summary

1. An isosceles triangle is an axially symmetrical figure. The axis of symmetry of an isosceles triangle is the perpendicular bisector of the base.

2. The height, midline and vertex bisector on the base of an isosceles triangle coincide (three lines merge into one)

3. The two base angles of an isosceles triangle are equal (equilateral sides to equal angles)

Decide whether the following statements are correct.

(1) The angle bisector, midline and altitude of an isosceles triangle coincide with each other. ( )

(2) There is an isosceles triangle with an angle of 60°, and the other two interior angles are also 60°. ( )

(3) The base angles of an isosceles triangle are all acute angles. ( )

(4) An obtuse triangle cannot be an isosceles triangle. ( )

training ground

1. In △ABC, AB=AC, ∠A=70°, then ∠B=______

2. The exterior angle of a base angle of an isosceles triangle is 105°, then its vertex angle is ______ degrees

3． The angle between the height of one waist of an isosceles triangle and the other waist is 60°, then the vertex angle of this isosceles triangle is ( )

A． 30°B． 150°C. 30° or 150° D. 120°

4. As shown in the figure, in △ABC, AB=AC, ∠A=36°, BD and CE are the angle bisectors of △ABC and △BCD respectively, then the isosceles triangle in the figure has ( )

A.5 B.4 C.3 D.2

Summary and sublimation

Properties of isosceles triangle

1. An isosceles triangle is an axially symmetrical figure. The axis of symmetry of an isosceles triangle is the perpendicular bisector of the base.

2. The height, midline and vertex bisector on the base of an isosceles triangle coincide (three lines merge into one)

3. The two base angles of an isosceles triangle are equal (equilateral sides to equal angles)

Determination of isosceles triangle

A triangle with two equal angles is an isosceles triangle

Rule and compass drawing

Construct an isosceles triangle if the base and height of the base are known

Test in class

1. An isosceles triangle has a base angle of 70° and its vertex angle is ______.

2. One angle of an isosceles triangle is 70°, and its other two angles are _______.

3. As shown in the figure, in the isosceles triangle ABC, AB=AC, D is the midpoint of BC, then the distance from point D to AB and AC is equal. Please explain why.

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"Isosceles Triangle" PPT Courseware 6:

"Isosceles Triangle" PPT Courseware 6

The concept of isosceles triangle

A triangle with two equal sides is called an isosceles triangle.

Two equal sides are called waist

The other side is called the bottom side

The angle between the two waists is called the vertex angle

The angle between the waist and the bottom is called the bottom angle...

"Isosceles Triangle" PPT courseware 5:

"Isosceles Triangle" PPT courseware 5 Experimental exploration Draw an isosceles triangle ABC on the paper, fold the paper in half so that its two waists AB and AC coincide, mark the intersection of the fold and the base as D, and then unfold the paper To lay the ground, think about the following questions: Question (1) Isosceles III..

"Isosceles Triangle" PPT courseware 3:

"Isosceles Triangle" PPT Courseware 3 Please tell me 1. What are the properties of an isosceles triangle? 2. How to determine whether a triangle is an isosceles triangle? 3. What are the special properties of an equilateral triangle? An equilateral triangle is an axis-symmetric figure and has three axes of symmetry. An equilateral triangle...

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Update Time: 2024-10-03

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

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