"Positional Similarity of Figures" PPT courseware

Description

"Positional Similarity of Figures" PPT courseware

1. What transformations of graphics have we learned before?

Symmetry (axial symmetry and axisymmetric graphics, central symmetry and central symmetric graphics): axis of symmetry, center of symmetry.

Translation: the direction of translation and the distance of translation.

Rotation: rotation center, rotation direction, rotation angle.

Similar: similar ratio.

Note: These different transformations of graphics are indispensable and important tools for us to learn geometry. It not only decorates our lives, but also is the basis for learning subsequent knowledge.

observe

Are the polygons in the pictures similar? If so, what are the characteristics of this similarity?

The two polygons in each picture are not only similar, but the lines connecting the corresponding vertices intersect at one point. Two figures like this are called similarity figures, and this point is called the similarity center.

Concepts and properties

Bit-like concept

Two similar polygons whose corresponding sides are parallel to each other (or collinear) and where the straight lines of each pair of corresponding points pass through the same point are called similarity figures, and this point is called the similarity center.

think about it

1. Determine whether the square below resembles a figure?

Obviously, bit-similar figures are a special case of similar figures. Similar figures are not necessarily bit-similar figures, but bit-similar figures must be similar figures.

2. Properties of bit-like figures

Property: The ratio of the distance between any pair of corresponding points on the similarity figure to the center of the similarity is equal to the similarity ratio.

Using bitmap, you can enlarge or reduce a figure.

For example, to reduce the quadrilateral ABCD to 1/2 of its original size,

1. Select any point O outside the quadrilateral (as shown in the picture),

2. Pick points A', B', C', and D' on the line segments OA, OB, OC, and OD respectively, so that OA'/OA=OB'/OB=OC'/OC=OD'/OD=1/ 2

3. Connect the points A', B', C', and D' in sequence, and the resulting quadrilateral A'B'C'D' is the required figure.

Explore

Is there any other way to solve the above problem? If you choose any point O outside the quadrilateral, take A', B', C', and D' on the reverse extension lines of OA, OB, OC, and OD respectively,

What about making OA'/OA=OB'/OB=OC'/OC=OD'/OD=1/2? What if point O is taken inside quadrilateral ABCD? Draw the graphs obtained at this time.

2. As shown in the figure, with O as the center, enlarge △ABC to twice its original size.

①Make rays OA, OB, OC

② Pick points A', B', and C' on OA, OB, and OC respectively so that

OA'/OA=OB'/OB=OC'/OC=1/2

③Connecting A', B', and C' in sequence is the required graphic

Keywords: teaching courseware on the positional resemblance of graphics, Qingdao version ninth grade mathematics volume PPT courseware download, ninth grade mathematics slide courseware download, positional resemblance of graphics PPT courseware download, .PPT format;

For more information about the "Position of Graphics" PPT courseware, please click on the "Position of Graphics" ppt tab.

"Positional similarity of similar polygons and figures" PPT courseware 2:

"Positional Similarity of Similar Polygons and Figures" PPT Courseware 2 1. If two ________ polygons ____________________ intersect at one point, we call the two figures similar figures. The intersection point is called ________, and the similarity ratio at this time is also called __..

"Positional Similarity of Similar Polygons and Figures" PPT courseware:

"Positional Similarity of Similar Polygons and Figures" PPT courseware 1. Two polygons with corresponding angles ________ and corresponding sides ________ are called ________. 2. The ratio of the perimeters of two similar polygons is equal to their __________; the ratio of the areas of similar polygons is equal to their _..

"Positional similarity of graphics" PPT courseware 2:

"Positional similarity of graphics" PPT courseware 2 Pre-class review: What is positional similarity of graphics? That is, its characteristics are: similar, the lines connecting the corresponding points intersect at one point; the corresponding line segments are parallel (or collinear). What shape do you get by connecting the following points in sequence? (00) (60) (64) (04) (0 ..

File Info

Update Time: 2024-10-27

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

Preview