"Similarity of Graphics" similar PPT courseware

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"Similarity of Graphics" similar PPT courseware

Review of knowledge points and test points:

1. Proportion:

1. Proportion: If the ratio of a:b and c:d is equal, we say that these four numbers a, b, c, d are proportional, and write the proportional formula a:b=c:d.

2. The fourth proportional term: If a/b=c/d, then d is called the fourth proportional term of a, b, c.

3. The middle term of the ratio: If a/b=c/d=bc, then b is called the middle term of the ratio of a and c.

2. Nature of proportion

Basic properties of proportion: a/b=c/d ad=bc(b≠0, d≠0); a/b=b/c --- b2=ac

proportional line segment

1. Ratio of line segments: Select the ratio of the lengths of two line segments with the same length unit.

2. Proportional line segments: Among four line segments, if the ratio of two line segments is equal to the ratio of the other two line segments, then these four line segments are called proportional line segments, or proportional line segments for short.

Similar polygons: Two polygons with equal angles and proportional sides. (The symbol for similarity is "∽") The ratio of corresponding sides is called the similarity ratio.

1. The definition of similar triangles: triangles whose corresponding angles are equal and corresponding sides are proportional.

2. Explore the conditions under which two triangles are similar:

Decision Theorem 1: Two triangles with equal angles are similar.

Determination Theorem 2: The two sides are proportional and the angles between them are equal, so the two triangles are similar.

Decision Theorem 3: Two triangles with three corresponding proportional sides are similar.

Analysis of typical examples

[Example 1] (2003·Nanjing City) On the Nanjing traffic tour map with a scale of 1:38000, the Xuanwu Lake Tunnel is about 7cm long, and its actual length is about ( )

A.0.266km B.2.66km

C.26.6km D.266km

[Example 2] Suppose 2a-3b=0, then a/b=3/2, a-b/b=1/2

【Example 6】

(1) If the 10 cm line segment is divided into golden sections, then the length of the longer line segment is _______ cm.

(2) Bend a 2-meter steel wire into a rectangular frame, and make the ratio of the width and length of the rectangular frame into the golden ratio, then the area of ​​the rectangle is __________.

(3) Assume P and Q are two golden section points on line segment AB, and PQ=a, then AB=___________.

【Example 7】

1. Which of the following propositions is correct ( )

A. All right triangles are similar

B. All isosceles triangles are similar

C. All isosceles right triangles are similar

D. None of the above conclusions are correct

2. As shown in the figure, in the parallelogram ABCD, G is a point on the extension line of BC, AG and BD intersect at point E, and DC intersects at point F, then there are ( ) similar triangles in the figure.

A.3 pairs B.4 pairs

C.5 pairs D.6 pairs

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For more information about the "Similarity of Similar Figures" PPT courseware, please click the Similar ppt tag of similar ppt graphics.

"Similarity of Figures" Similarity PPT Courseware 3:

"Similarity of Figures" Similarity PPT Courseware 3 Learning Objectives 1. Recognize the similarity of figures from examples of figures with the same shape in life and understand the concept of similar figures; 2. Understand the properties and judgment of similar figures. The properties of similar polygons: Similarity Corresponding angles of polygons...

"Similarity of Figures" Similarity PPT Courseware 2:

"Similarity of Figures" Similarity PPT Courseware 2 Teaching Objectives Knowledge and Ability Perceive the application of similar graphics in reality. Recognize shapes with the same shape. Understand the basic connotation of similar graphics. Process and methods: Understand the process of similar graphics through observation and operation. ..

"Positional Similarity of Figures" Similarity of Figures PPT Courseware 3:

"Positional Similarity of Figures" Similarity of Figures PPT Courseware 3 1. The concept of quasi-similar figures. If two figures are not only similar, but also the straight lines of each set of corresponding vertices pass through the same point, and the corresponding sides are parallel to each other (or collinear), then such two figures are called quasi-similar figures..

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Update Time: 2024-11-03

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

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