"Busy Construction Site" PPT Courseware 4

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"Busy Construction Site" PPT Courseware 4

1. The figure formed by two rays drawn from a point is called an angle.

How are these three corners drawn?

Draw a point first, and then draw two rays.

2. Names of each part of the angle and how to express the angle.

Angle is usually represented by the symbol " ", pronounced: "angle"

(Note the difference with the less than sign "�".)

If there are several corners, number them respectively (write 1, 2, 3, etc. inside the corner)

They are recorded as: ∠1, ∠2, ∠3.

1. Protractor

The unit of measurement for angle is "degree", represented by the symbol "°". Divide the semicircle into 180 equal parts, and the angle subtended by each part is called a first-degree angle. Record it as "1°".

2. Steps to measure angles with a protractor:

1. Place the protractor on top of the angle; make the center of the protractor coincide with the vertex of the angle;

2. The zero-degree scale line coincides with one side of the angle;

3. The scale on the protractor opposite the other side of the angle is the measure of the angle.

3. Steps to draw a 65° angle:

(1) Draw a ray so that the center of the protractor coincides with the endpoint of the ray, and the 0 scale line coincides with the ray.

(2) Click a point at the 65° mark of the protractor.

(3) Taking the endpoint of the drawn ray as the endpoint, draw another ray through the point just drawn.

(4) After drawing, mark the corners with symbols and write the degrees.

How to draw a 15° angle using a triangle?

You can use a triangle ruler to draw angles of 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, 150°, 165°, and 180°. There are so many angles! You can use a protractor to draw other angles!

Consolidation exercises

Draw angles of 30°, 45°, 60°, 90°, and 120°.

Keywords: Busy Construction Site Teaching Courseware, Qingdao Edition Fourth Grade Mathematics Volume 1 PPT Courseware Download, Fourth Grade Mathematics Slide Courseware Download, Busy Construction Site PPT Courseware Download, .PPT format;

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Update Time: 2024-09-04

This template belongs to Mathematics courseware Qingdao Edition Fourth Grade Mathematics Volume 1 industry PPT template

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