"Interior and exterior angles of a triangle" PPT download

Description

"Interior and exterior angles of a triangle" PPT download

Part 1: Think about it

What is the sum of the three interior angles of a triangle?

Is there any way you can verify this?

Tip: Try putting three corners together

Proof: As shown in the figure:

Extend BC to CD as CE∥AB

Then ∠1=∠A

(Two straight lines are parallel and their internal offset angles are equal)

∴∠B=∠2

(Two straight lines are parallel and have equal angles).

Also ∵∠1+∠2+∠ACB=180°

(Sum of interior angles of a triangle theorem)

∴∠A+∠B+∠ACB=180° (equivalent substitution)

Conclusion: The sum of the interior angles of a triangle is equal to 180°.

Interior angles and exterior angles of triangles PPT, Part 2 content: Application of new knowledge

(1) In △ABC, ∠A=35°, ∠B=43°

Then ∠ C=______.

(2) In △ABC, ∠A :∠B:∠C=2:3:4

Then ∠A =______ ∠ B=______ ∠ C=______ .

discuss

(1) How many ____ right angles are there in a triangle? why?

(2) There are at most ____ obtuse angles in a triangle? why?

(3) There are at least ____ acute angles in a triangle? why?

(4) In any triangle, the largest angle has a measure of at least ____.

Interior angles and exterior angles of a triangle PPT, Part 3 content: Class topics

1. As shown in the picture, a classmate broke a triangular piece of glass into three pieces. Now he wants to go to a glass shop to get a piece of glass with exactly the same shape. So the easiest way is ()

(A) Take ① with you (B) Take ② with you (C) Take ③ with you (D) Take ① and ② with you

2 In △ABC, ∠A=80°, ∠B=∠C, find the degree of ∠C.

Solution: In △ABC,

∠A+∠B+∠C=180°, ∠A=80°

∴∠B+∠C=100°

∵∠B=∠C

∴∠B=∠C=50°

3. It is known that the ratio of the measures of the three interior angles of a triangle is 1:2:3. Find the measures of these three interior angles.

Solution: Let the three interior angles be: x, 2x, 3x.

List the equation x+2x+3x=180°

x=30°

Answer: The three internal angles are 30°, 60° and 90° respectively.

Conclusion: The two acute angles of a right triangle are mutually supplementary

Interior angles and exterior angles of triangles PPT, Part 4 content: Tracking exercises:

1In △ABC, if ∠A＋∠B＝∠C, then △ABC is ( )

A. Acute angle △ B. Right angle △ C. Obtuse angle △ D. Isosceles △

2 A triangle has at least ( )

A. One acute angle B. Two acute angles C. One obtuse angle D. One right angle

Keywords: Free download of Hebei Education Edition mathematics PPT courseware for seventh grade volume 2, interior and exterior angles of a triangle PPT download, .PPT format;

For more information about the "Interior and Exterior Angle of a Triangle" PPT courseware, please click on the "Interior and Exterior Angle of a Triangle ppt" tab.

"Interior and Exterior Angle of Triangle" PPT courseware:

"Interior Angle and Exterior Angle of a Triangle" PPT courseware Part One Content: Interior Angle and Exterior Angle of a Triangle Review Questions: 1. What are the interior angles of a triangle? 2. What is the relationship between the three interior angles of a triangle? Jigsaw Puzzle: Tear off the three interior angles of a triangle..

"Interior and Exterior Angle of Triangle" PPT:

"Interior Angle and Exterior Angle of Triangle" PPT Part One Content: Review the past and learn new things 1. Related concepts of triangles: 1. What is a triangle: A figure composed of three line segments that are not on the same straight line and are connected end to end is called a triangle. 2. Vertex: Use a big...

File Info

Update Time: 2024-10-05

This template belongs to Mathematics courseware Hebei Education Edition Seventh Grade Mathematics Volume 2 industry PPT template

Preview