"Isosceles Triangle" PPT Courseware 3

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"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 equilateral triangles.

An equilateral triangle is an axially symmetrical figure and has three axes of symmetry.

Each angle of an equilateral triangle is equal to 60°.

What are some ways to determine an equilateral triangle?

A triangle with 3 equal angles is an equilateral triangle.

A triangle with two angles equal to 60° is an equilateral triangle.

An isosceles triangle with one angle equal to 60° is an equilateral triangle.

Example 1 is shown in the figure. In △ABC, AB=AC, ∠BAC=1200, AD⊥AB, AE⊥AC.

⑴In the picture, the angle equal to 300 has __________, and the angle equal to 600 has _______;

⑵△ADE is an equilateral triangle? Why?

⑶In Rt△ABD, ∠B=_____, AD=_____BD; in Rt△ACE, is there a similar conclusion?

Example 2 As shown in the figure, in △BAC, ∠BAC=900 AB=AC, point D is on BC, and BD=BA, point E is on the extension line of BC, and CE=CA. Try to find the degree of ∠DAE.

Example 3. As shown in the figure, △ABC and △CDE are both equilateral triangles, and points A, C, and E are on a straight line.

(1) AD=BE? Why?

(2) Is △MNC an equilateral triangle? Why?

Explore independently

As shown in the figure, AC=BC, and AC⊥BC, D is a point on AC, BD=2AE, AE⊥BE, prove: BE bisects ∠ABC.

Challenge yourself

Given a square piece of paper, can you fold it into an equilateral triangle without any tools and only one pair of hands? If so, please explain the specific steps.

Teaching reflection

How does it help us to master the properties of an isosceles triangle?

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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 4:

"Isosceles Triangle" PPT Courseware 4 Course Standard Requirements Explore and prove the property theorem of an isosceles triangle: The two base angles of an isosceles triangle are equal; the altitude line, midline and vertex angle bisector on the base coincide (three lines merge into one). Explore and master the determination theorem of isosceles triangles..

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Update Time: 2024-10-04

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

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