"Projection" Projection and View PPT Courseware 7

Description

"Projection" Projection and View PPT Courseware 7

learning target

1. Understand the concepts of projection, projection plane, parallel projection and central projection;

2. Pay attention to mathematical problems related to projection in life and improve the application awareness of mathematics.

Generally, when an object is illuminated with light, the shadow obtained on a certain plane (floor, wall, etc.) is called the projection of the object.

The irradiating light is called the projection line, and the plane on which the projection is located is called the projection surface.

Definition Sometimes a light ray is a group of parallel rays, such as the rays in a beam of sunlight or searchlight. The projection formed by parallel rays is a parallel projection.

For example: the shadow formed by an object under sunlight (referred to as sun shadow) is parallel projection. The direction of the sun's shadow can reflect time. The timepiece sundial in ancient my country observed time based on the sun's shadow.

central projection

For example, if an object forms a shadow under the light from a light bulb, it is a central projection.

Thinking: What are the differences and connections between parallel projection and central projection?

[Example 1] (1) Are they the rays of the sun or the rays of lights?

They are the rays of light!

They are not parallel rays, they are divergent rays

[Example 2] Determine the location of the street light bulb in the picture.

[Analysis] Draw a straight line through the top of a wooden pole and its shadow end, and then draw a straight line through the top of another wooden pole and its shadow end. The two straight lines intersect at point O. Point O is the location of the street light bulb.

Practice in class

1. The length of a person’s shadow when he leaves the light ( )

A. unchanged B. shortened C. lengthened D. uncertain

2. The shadows of two objects under the same light can be ( )

A. Same direction B. Different directions

C. Opposite direction D. All of the above are possible

3. At the same moment, two poles of different lengths are placed under the sun, but their shadow lengths are equal, then the relative positions of the two poles are ( )

A. Both poles are perpendicular to the ground. B. Two parallel poles are inserted diagonally into the ground.

C. The two poles are not parallel. D. One fell to the ground.

Keywords: Projection and view teaching courseware, projection teaching courseware, New People's Education Edition ninth grade mathematics second volume PPT courseware, ninth grade mathematics slide courseware download, projection and view PPT courseware download, projection PPT courseware download, .ppt format

For more information about the "Projection and View" PPT courseware, please click on the "Projection ppt Projection and View ppt" tab.

Projector curtain whiteboard PPT background picture:

This is a projector curtain whiteboard PPT background picture; Keywords: curtain, whiteboard PowerPoint background picture, still life slide background picture, .jpg format;..

"Projection" PPT courseware:

"Projection" PPT courseware Part One: Introduction of new lesson Do you know the relationship between objects and shadows? When objects are illuminated by sunlight or lights, they will form shadows on the ground, walls, etc. It can be seen that shadows are closely related to the shape of objects. Object and its...

"Projection" PPT:

"Projection" PPT Part One Content: Concept The light of candles and light bulbs can be seen as emitting from one point. Like this, the projection formed by the light emitted from a point shining on the object is called central projection. Sun rays and searchlights...

File Info

Update Time: 2024-09-14

This template belongs to Mathematics courseware People's Education Press Ninth Grade Mathematics Volume 2 industry PPT template

Preview