"Line, Ray, Line Segment" Preliminary PPT Courseware on Geometric Figures (Lesson 2)

Description

"Line, Ray, Line Segment" Preliminary PPT Courseware on Geometric Figures (Lesson 2)

Part One: Learning Objectives

1. Can use a ruler to draw a line segment equal to a known line segment, and can compare the length of two line segments. (Key points)

2. Understand the meaning of bisecting points of line segments.

3. Be able to use the relationship between the sum, difference, multiple and division of line segments to find the length of a line segment. (Key points and difficulties)

4. Understand the mutual transformation of written language, symbolic language and graphic language.

5. Understand the meaning of the distance between two points, understand the properties of the line segment "between two points, the shortest line segment", and learn to use it. (Difficulty)

Straight line ray segment PPT, part 2: introduction of situations

In the three groups of figures, the lengths of line segments a and b are all equal.

Observing these three sets of figures, can you compare the lengths of line segments a and b in each set of figures?

Many times, seeing is not necessarily believing. Accurately comparing the lengths of line segments requires more rigorous methods.

Straight line ray segment PPT, the third part content: comparison of length of line segments

collaborative inquiry

When doing manual work, if we want to cut a section from a longer wooden stick without a scale so that the cut wooden stick is equal to the length of another short wooden stick, we often use the above method.

Thinking: The line segment drawn on the blackboard cannot be moved. If you only have a compass and a ruler without a scale, please think of a way to draw a line segment that is equal to it?

Tips: Within the maximum range of opening angles, the compass can be cut to any length, which is equivalent to a movable "small wooden stick".

Construct a line segment equal to the known line segment

Given: line segment a, construct a line segment AB such that AB=a.

Step 1: Use a ruler to draw ray AF;

Step 2: Use a compass to intercept AB = a on ray AF.

∴ Line segment AB is what is required.

In mathematics, we usually use an unscaled ruler and compass to draw, which is called ruler and compass drawing.

Straight line ray segment PPT, part 4 content: sum, difference, times and points of line segments

draw a picture

Draw line segment AB=a on the straight line, and then draw line segment BC=b on the extension line of AB. Line segment AC is the sum of ____ and ____, recorded as AC=____. If you draw line segment BD= on AB b, then line segment AD is the difference between ____ and ____, recorded as AD=____.

Do it

1. As shown in the figure, points B and C are on the line segment AD, then AB+BC=____; AD-CD=___; BC= ___ -___= ___ - ___.

2. As shown in the figure, given line segments a and b, draw a line segment AB so that AB=2a-b.

Analysis of classic examples

Example 1 If AB = 6cm, point C is the midpoint of line segment AB, and point D is the midpoint of line segment CB. Find: What is the length of line segment AD?

Example 2 As shown in the figure, B and C are two points on the line segment AD, and AB: BC: CD=3:2:5. E and F are the midpoints of AB and CD respectively, and EF=24. Find the line segments AB and BC. , CD length.

Method summary: When finding the length of a line segment, when the question involves the ratio or multiple relationship of the length of the line segment, you can usually set the unknown number and use equation thinking to solve the problem.

Straight line ray segment PPT, part 5: basic facts about line segments

Discuss

As shown in the picture: There are four roads from A to B. In addition to them, can another shortest road be built from A to B? If you can, please draw the shortest route on the map based on the knowledge you have learned before.

After comparison, we can get a basic fact about the line segment:

Among all the lines connecting two points, the line segment is the shortest. Simply put:

Between two points, the line segment is the shortest.

The length of the line segment connecting two points is called the distance between the two points.

Straight line ray segment PPT, Part 6 content: Practice in class

1. Which of the following statements is correct ( )

A. The definition of distance between two points refers to the line segment between two points

B. The distance between two points refers to the straight line between the two points

C. The distance between two points refers to the length of the line segment connecting the two points.

D. The distance between two points is the length of the straight line between the two points

2. As shown in the figure, AC = DB, then the other two equal line segments in the figure are _____________.

3. Given that line segment AB = 6 cm, extend AB to C so that BC = 2 AB. If D is the midpoint of AB, then the length of line segment DC is ________.

4. Points A, B, and C are on the same number axis. The numbers represented by points A and B are -3 and 1 respectively. If BC=5, then AC=___________.

Keywords: Free download of PPT courseware for seventh-grade mathematics from the People's Education Press, PPT download of straight lines, rays and segments, preliminary PPT download of geometric figures, .PPT format;

For more information about the "Preliminary Linear Ray Segments of Geometric Figures" PPT courseware, please click the Preliminary Geometric Figures PPT Linear Ray Segments PPT tab.

"Line, Ray, Line Segment" Preliminary PPT Courseware on Geometric Figures (Lesson 1):

"Line, Ray, Line Segment" Preliminary PPT Courseware on Geometric Figures (Lesson 1) Part One: Learning Objectives 1. Master the basic facts that two points determine a straight line, and understand the positional relationship between points and straight lines. 2. Further understand straight lines and rays , line segments, will use the correct...

"Line, Ray, Line Segment" Preliminary PPT of Geometric Figures (Lesson 2):

"Straight Lines, Rays, Line Segments" Preliminary PPT on Geometric Figures (Lesson 2) Part One: Learning Objectives 1. Be able to use a ruler to draw a line segment equal to a known line segment, and be able to compare the length of two line segments. (Key Points) 2. Understand The meaning of bisecting points of line segments. 3. Be able to use lines..

"Line, Ray, Line Segment" Preliminary PPT of Geometric Figures (Lesson 1):

"Line, Ray, Line Segment" Preliminary PPT on Geometric Figures (Lesson 1) Part One: Learning Objectives 1. Master the basic facts that two points determine a straight line, and understand the positional relationship between points and straight lines. 2. Further understand straight lines, rays, Line segments will use the correct...

File Info

Update Time: 2024-07-06

This template belongs to Mathematics courseware People's Education Press Seventh Grade Mathematics Volume 1 industry PPT template

Preview