"Angle" Geometric Figures Preliminary PPT Courseware

"Angle" Geometric Figures Preliminary PPT Courseware

Part One: Learning Objectives

1. Understand the two definitions of angles and related concepts, and master the expression method of angles. (Key points)

2. Be able to use a protractor correctly to measure angles.

3. Understand the units of angles and be able to convert between degrees, minutes and seconds. (Key points and difficulties)

Situation introduction

Observing the objects on the left, what common image do you find that these objects can abstract?

--horn

Angle PPT, the second part of the content: the definition of angle

Can you summarize the characteristics of the horn? In your own words, describe the shape that an angle is made of?

Knowledge points

Concepts related to angle

Static definition: A figure composed of two rays with common endpoints is called an angle.

Dynamic definition: An angle can also be viewed as a figure formed by a ray rotating around its endpoint.

Think about it: As shown in the figure, ray OA rotates around point O. When the end position OB and the starting position OA are in a straight line, what angle is formed? Continuing the rotation, what angle will they form when OB and OA coincide?

practice

1. Determine which of the following figures are angles

2. Which of the following statements is correct ( )

A. A straight angle is a straight line

B. A ray is a circumferential angle

C. The figure formed by two rays is called an angle

D. An angle with two sides in a straight line is a straight angle.

Angle PPT, the third part: the representation method of angle

Think about it, what are the ways to represent angles?

Knowledge points

How to express angle

1. Indicated by three capital letters, such as: ∠AOB or ∠BOA;

When two or more angles share a vertex, they cannot be represented by a capital letter.

2. Express it with a number, such as ∠1;

3. Expressed by lowercase Greek letters, such as ∠α.

practice

1. There are _____ corners in the picture. Can you represent them?

∠AOE, ∠COE, ∠AOC.

2. Fill in the table below and express the angles in the figure in different ways.

Angle PPT, Part 4 content: Measurement of angles

How do you know the size of this angle?

Angle measuring tool: protractor

We commonly use protractors to measure angles. Degrees, minutes, and seconds are commonly used units of angle measurement. Divide a circumferential angle into 360 equal parts, and each part is an angle of 1 degree, recorded as 1°; divide an angle of 1 degree into 60 equal parts, Each portion is called the angle of 1 cent, and is recorded as 1′; divide the angle of 1 cent into 60 equal parts, and each portion is called the angle of 1 second, and is recorded as 1″.

Analysis of classic examples

Example 1 Conversion of degrees, minutes and seconds

(1) 57.32°=_____°_____′_____″;

Example 2 As shown in the figure, when the clock displays 10:10, the angle between the hour hand and the minute hand is ()

A． 90°B. 100°C． 105° D. 115°

Corner PPT, Part 5: Practice in class

1. Which of the following statements is correct ( )

A. When two straight lines intersect, the shape formed is called an angle.

B. The figure composed of two line segments with common endpoints is called an angle.

C. The figure formed by two rays with a common point is called an angle.

D. The figure formed by two rays drawn from the same point is called an angle

2. Which of the following statements is incorrect ( )

A. The vertex of ∠AOB is O

B. Rays BO and AO are the two sides of ∠AOB respectively.

C. The sides of ∠AOB are two rays

D. ∠AOB and ∠BOA represent the same angle

3. When four students A, B, C, and D judged the time when the minute hand and hour hand of the clock were perpendicular to each other, each of them said two times, and they were all correct ()

A． A: "3 o'clock and 3:30"

B. Person B said "6:15 and 6:45"

C． C said "9 o'clock and 12:15"

D． Ding said: "3 o'clock and 9 o'clock"

Corner PPT, Part Six: Class Summary

angle definition

A graph composed of two rays with common endpoints

A figure formed by a ray rotating around its endpoints

How to express angle

Indicated by three capital letters or one capital letter

Represented by a number plus an arc

Represented by a lowercase Greek letter followed by an arc

measure of angle

Degrees, minutes, seconds

1°=60′, 1′=60″

Keywords: Free download of seventh-grade mathematics PPT courseware from People's Education Edition, download of angle PPT, download of preliminary PPT of geometric figures, .PPT format;

For more information about the "Preliminary Angular Geometric Figures" PPT courseware, please click the Preliminary Angle PPT Geometric Figures PPT tab.

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