"Position Similarity" Similar PPT Courseware 2

Description

"Position Similarity" Similar PPT Courseware 2

Review and Reflection

1. What transformations of graphics have we learned before?

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

Rotation: center of rotation, direction of rotation, angle of rotation. (Specifically, center symmetry)

Axisymmetric

Let's learn a new graphic transformation bit likeness together

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.

learning target

Master the definition of similitude figures, the difference and connection between similitude and similarity, and how to draw similitude figures.

Through the process of understanding, operating, and summarizing parallel graphics, students are stimulated to be interested in exploring problems, gain the joy of successfully solving problems, and cultivate a sense of cooperation and communication among students.

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

The two polygons are not only similar, but the lines connecting the corresponding vertices intersect at one point, and the corresponding sides are parallel to each other. Two figures like this are called homothetic figures, and this point is called the homothetic center. The similarity ratio at this time is also called The position is similar.

think about it

What should we do to reduce the size of quadrilateral ABCD to 1/2 of its original size?

1. Pick any point O outside the quadrilateral

2. Make rays OA, OB, OC, OD

3. Take A’, B’, C’ and D’ respectively on OA, OB, OC and OD, so that OA’/OA=OB’/OB=OC’/OC=OD’/OD

4. Connect A’, B’, C’, and D’ in sequence, and the resulting quadrilateral is the desired

Practice expansion

1. As shown in the figure, △OAB and △OCD are similar figures. Are AB and CD parallel? Why?

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

Class summary

The concept of bit-like graphics:

If two figures not only have the same shape, but also the straight lines of each set of corresponding vertices pass through the same point, then such two figures are called similarity figures, and this point is called the similarity center. The similarity ratio at this time is also called similarity. Compare.

The relationship between similarity and resemblance

Similar figures must be similar figures, but similar figures are not necessarily similar figures.

Bit-like drawing method

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"Position-like Figures" PPT courseware:

"Positionally Similar Figures" PPT Courseware Observation and Thinking In the following figures, the quadrilateral ABCD and quadrilateral ABCD in each figure are similar figures. Observe these five figures separately, you find that the two quadrilaterals in each figure correspond to the points What are the characteristics of connections? Clear new knowledge such as...

"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 _..

File Info

Update Time: 2024-11-17

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

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