Line test - graphic reasoning - 3 - symmetric graphic class

When it is observed that the graphics are regular but the elements are messy , We can consider the investigation of symmetry .

This article will mainly focus on the topic of investigating symmetric properties , The symmetrical examination method has the following aspects ：

The following examples are given for different types ：

Catalog

One 、 Symmetrical type

Two 、 Axis of symmetry  

1. Number of symmetry axes

2. Axis of symmetry direction

3. Included angle of axis of symmetry

4. The relationship between the axis of symmetry and the position of the figure

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One 、 Symmetrical type

（1）

1,3,6 Is a symmetrical figure ;2,4,5 It is an asymmetric figure .

（2）

  The figures are axisymmetric 、 Centrosymmetry 、 axial symmetry 、 Centrosymmetry 、 axial symmetry , Next select the centrosymmetric figure C.

 （3）

 1,2,4 It is an axisymmetric figure ;3,5,6 It is a centrosymmetric figure .

Two 、 Axis of symmetry  

1. Number of symmetry axes

（1）

The number of axes of symmetry is 1,2,3,4, Therefore, the number of symmetry axes selected is 5 Of D.

（2）

  The number of symmetry axes of the first group of figures is 0,1,2; Therefore, the number of symmetry axes selected in the second group of figures is 1 And the direction of the axis of symmetry points to the upper left 45 Degree B.

 （3）

 1,4,5 There are two axes of symmetry ;2,3,6 There is an axis of symmetry .

2. Axis of symmetry direction

（1）

The symmetry axis of the first group of figures rotates clockwise 45 degree ; So choose C（B It's an ellipse ）.

（2）

Find rules by line , The axis of symmetry rotates clockwise 45 degree . So choose B.

 （3）

The direction of the axis of symmetry rotates clockwise 45 degree , So choose A.

 （4）

The direction of symmetry axis of each group of figures is consistent , So choose A.

 

3. Included angle of axis of symmetry

（1）

Each figure consists of two small figures , The included angle of the symmetry axis of these two small figures is 180 degree 、45 degree 、90 degree , So choose D.

 （2）

 

  The included angle of the symmetry axis of the first group of figures and the two small figures is 90 degree ; The angle between the two small figures of the second group of figures is 180 degree , So choose D

4. The relationship between the axis of symmetry and the position of the figure

（1）

Observe the direction of the symmetry axis of each figure , It can be ruled out by the direction law of the axis of symmetry AC. Then observe from the first figure , The axis of symmetry coincides with an edge of the original image 、 vertical 、 coincidence 、 vertical 、 coincidence , Therefore, choose non coincident B.

 （2）

Locked by the direction of the axis of symmetry AC, Then observe whether the symmetry axis coincides with the edge of the original image to know the answer C.

（3）

 

 1,4,5 The axis of symmetry intersects with the original image ;2,3,6 The axis of symmetry intersects the original image at a point .