"Determination of Parallel Lines" PPT courseware

Description

"Determination of Parallel Lines" PPT courseware

Knowledge review

As shown in the figure, points B, A, and E are on a straight line. If AD∥BC, then:

(1) ∠1=∠B, based on the fact that the two straight lines are parallel and the angles are equal.

(2) ∠2=∠C, the basis is that the two straight lines are parallel and the internal offset angles are equal.

(3) ∠DAB+∠B =180°, based on the fact that two straight lines are parallel and the interior angles on the same side are complementary.

Experimentation and inquiry

How can we determine that two straight lines are parallel?

If two straight lines are intercepted by a third straight line, then the two straight lines are parallel if the angles are equal.

Communication and discovery:

1. As shown in the figure, ∠1=∠2, are straight line a parallel to straight line b? Why?

2. As shown in the figure, ∠1 and ∠2 are complementary. Are line a and line b parallel? Why?

From this, what method can be obtained to determine whether two straight lines are parallel?

The internal offset angles are equal and the two straight lines are parallel;

Interior angles on the same side are complementary and two straight lines are parallel.

give it a try

As shown in the figure, if ∠1=∠A and ∠2=∠B, then is the straight line EF∥DC? Why?

Solution: Because ∠1=∠A, so AB∥EF, (the parallel angles are equal and the two straight lines are parallel.)

Because ∠2=∠B, so AB∥DC, (the internal offset angles are equal and the two straight lines are parallel.)

Because AB∥EF, AB∥DC, therefore EF∥DC. (Two lines are parallel if they are both parallel to a third line.)

Application Exercises: Group A

1. As shown in the figure, D is a point on AC and F is a point on AB. Under what conditions can DF∥BC be determined? Explain the reason.

2. As shown in the figure, which two straight lines can be determined to be parallel according to the following conditions? and explain the reasons. (1)∠2=∠B; (2) ∠1=∠D; (3)∠3+∠F=

3. How many straight lines are there in the plane that are parallel to the known straight line a and whose distance is equal to 5 cm? Draw and see.

4. As shown in the figure, it is known that ∠1=∠2 and ∠3=110°. Find the degree of ∠4.

5. As shown in the figure, AD bisects ∠BAC, ∠1=∠3, can we deduce AB∥CD? Give reasons.

6. As shown in the figure, it is known that ∠MCA= ∠ A, ∠ DEC= ∠ B, then is DE∥MN? Why?

Knowledge summary

Fundamental contents

Two straight lines are intercepted by a third straight line. If the angles of the same angles are equal or the interior angles of the same side are equal or the interior angles on the same side are complementary, then the two straight lines are parallel.

Two lines are parallel if they are both parallel to a third line.

If two lines are parallel, then every point on one line is the same distance from the other line. This distance is called the distance between two parallel lines.

1. Solution: ∠1=∠C or ∠2=∠B or DF∥BC can be determined from ∠3+∠B=180° or ∠4+∠C=180°.

2. Solution:

(1) AB∥DE (the angles are equal and the two straight lines are parallel.)

(2) AC∥DF (the internal offset angles are equal and the two straight lines are parallel.)

(3) AC∥DF (The interior angles on the same side are complementary and the two straight lines are parallel.)

Keywords: Judgment of Parallel Lines Teaching Courseware, Qingdao Edition 7th Grade Mathematics Volume 2 PPT Courseware Download, 7th Grade Mathematics Slide Courseware Download, Judgment of Parallel Lines PPT Courseware Download, .PPT format;

For more information about the "Determination of Parallel Lines" PPT courseware, please click on the "Determination of Parallel Lines" ppt tab.

"Determination of Parallel Lines" PPT download:

"Determination of Parallel Lines" PPT Download Part 1 Content: Creation Problem We already know: the same angles are equal and the two straight lines are parallel. That is, in the figure, if 1=2, then AB∥CD. Application: ∵ 1=2, (already Know) AB∥CD (the angles are equal and the two straight lines are parallel)..

"Determination of Parallel Lines" PPT:

"Judgment of Parallel Lines" PPT Part One: Review Review: 1. Judgment: 1. If two straight lines do not intersect, they are called parallel lines. 2. There is only one straight line parallel to a straight line. 3. If straight lines a and b are both parallel to c, then a and b are parallel. 2. How to...

"Determination of Parallel Lines" PPT Courseware 2:

"Determination of Parallel Lines" PPT Courseware 2 Review Questions 1. How to determine parallel lines? 2. As shown in the figure below, please state all the direct conditions that can obtain the straight line AB∥CD, and explain the reasons. Feedback evaluation, game solitaire 1. If A=3, then AD∥BE (same angle...

File Info

Update Time: 2024-06-24

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

Preview