"Comparison of Angles" PPT Courseware 3

Description

"Comparison of Angles" PPT Courseware 3

learning target:

1. Learn to use the "superposition method" to compare the sizes of angles.

2. Know the relationship between the sum, difference, times and minutes of angles, and be able to express them in geometric language.

3. Know the definition of the bisector of an angle and be able to express it in geometric language.

1. Do you still remember?

How to compare the size of two line segments:

Method 1: Overlay method;

Method 2: Measurement method.

2. Experiments and research

1. Ask each student to randomly draw two angles ∠α and ∠β on the paper, and then cut them out. Can you compare their sizes?

Try it on your own first, then discuss the method in a group.

Coincide the vertices of ∠α and ∠β, then overlap one side of ∠α with one side of ∠β, and make the other sides of the two angles on the same side of the overlapping side.

If the other side of ∠ α falls inside ∠ β, then ∠α is said to be less than ∠β or ∠β is greater than ∠α.

Denoted as ∠α ＜ ∠β or ∠β ＞ ∠α

This method of comparing angle sizes is also called the superposition method.

Sum and difference of angles

∠AO B′= ∠AO B+ ∠A′O′ B′

∠A′O′ B′= ∠AO B′—∠AO B

give it a try

1. As shown in the figure, OC and OD are the angle bisectors of ∠BOD and ∠AOB respectively, then

∠BOC = ∠ ____=___ ∠BOD=_____ ∠AOC=____ ∠AOB

2. As shown in the figure, draw ray OB inside ∠ AOC and draw ray OD outside ∠ AOC. Which two angles are the sum of ∠ AOC? ∠ BOD is the sum of which two angles? When ∠ AOB = ∠ COD, can you find other equal angles?

Solution: It can be seen from the graph that

∠AOC= ∠AOB+∠BOC;

∠ BOD= ∠BOC+∠COD;

When ∠ AOB = ∠ COD,

∠ AOC= ∠ BOD.

On-site inspection:

1. Given ∠α, use a magnifying glass to magnify 10 times to see ∠α. The angle observed through the magnifying glass is ∠β, then ∠α______∠β

(Fill in ">", "<" or "=").

2. As shown in the figure, ①If AC bisects ∠BAD, then ∠_____=∠______;

②If ∠BCA=∠DCA, then CA is the bisector of ________.

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"Comparison of Angles" PPT Courseware 2:

"Comparison of Angles" PPT Courseware 2 Teaching Objectives: 1. Compare the sizes of angles based on figures 2. Understand the concept of the sum and difference of angles 3. Master the concept of angle bisectors 1. Superposition method (starting from shape) (1) Known ABC and DEF are as shown in the figure: 2. Measurement method (starting from numbers) The magnitude of the angle...

"Comparison of Angles" PPT courseware:

"Comparison of Angles" PPT courseware learning objectives: 1. Learn to use the superposition method to compare the sizes of angles. 2. Know the relationship between the sum, difference, times and minutes of angles, and be able to express them in geometric language. 3. Know the bisectors of angles Definition, and can express it in geometric language. 1. Do you still remember? ..

"Comparison of Angles" Basic Plane Graphics PPT Courseware 2:

"Comparison of Angles" Basic Plane Graphics PPT Courseware 2 Observation and Thinking: ① What details must be paid attention to when using the superposition method to compare the sizes of angles? ②Is the size of the angle related to the length of the drawn parts on both sides? According to the figure below, solve the following problems: (1) Compare AOB, A..

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Update Time: 2024-10-19

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

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