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  • 识别对称线

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    Symmetry is the key to the balance of a design or structure.
    ::对称是设计或结构平衡的关键。

    What is symmetry? How does an image have symmetry? What would you have to do to be sure that an image or construction was symmetrical?
    ::什么是对称性?一个图像怎么会有对称性?你需要做什么才能确定一个图像或构造是否对称?

    In this concept, you will learn to identify lines of symmetry.
    ::在这个概念中,你会学会辨别对称线。

    Symmetry
    ::对对称

    Sometimes, a figure will have parts that mirror themselves within one object. In this case, parts of the object match other parts of the picture. This is called symmetry .
    ::有时,图中会有一个物体内有反射部分。在这种情况下,对象的部分与图片中的其他部分相匹配。这叫做对称。

    Let’s look at an example.
    ::让我们举个例子。

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    Look at this heart. It has two sides that match. The heart is symmetrical because there is symmetry in its design. This heart can be divided in half vertically where one half matches the other half.
    ::看看这个心脏。 它有两个匹配的两面。 心脏是对称的, 因为它的设计有对称性。 这个心脏可以垂直地分成一半, 一半与另一半相匹配 。

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    This line that divides the heart into matching parts is called the line of symmetry .
    ::将心脏分隔为匹配部分的线条叫做对称线。

    You can determine other lines of symmetry by looking at other objects.
    ::您可以通过查看其他对象来确定其他对称线。

    Let’s look at another example.
    ::让我们再看看另一个例子。

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    Look at this cross. It has two lines of symmetry. If you look, the cross can be divided in half perfectly vertically and in half horizontally.
    ::看看这个十字架。 它有两行对称。 如果您看, 十字架可以垂直地分为两半, 水平地分为两半 。

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    This means that there are two lines of symmetry in the cross.
    ::这意味着十字架上有两行对称。

    Examples
    ::实例

    Example 1
    ::例1

    Earlier, you were given a problem about  questions on symmetry.
    ::早些时候,有人给了你一个关于对称问题的问题。

    1. What is symmetry?
    ::1. 什么是对称?

    Symmetry is when two halves of an object match. In other words, you can divide the object into parts and the parts are congruent . A heart is a symmetrical object, so is the letter A.
    ::对称性是对象两半匹配时的对称性。换句话说,您可以将对象分成几个部分,而部分是相同的。心脏是一个对称对象,字母A也是对称对象。

    2. How does an image have symmetry?
    ::2. 图像如何对称?

    An image has symmetry because it can be divided in half so that one half of the image matches the other half.
    ::图像具有对称性, 因为它可以分成一半, 这样一半的图像与另一半相匹配 。

    3. What would you have to do to be sure that your image was symmetrical?
    ::3. 要确定你的形象是否对称,你需要做些什么?

    For an image to have a line of symmetry the image must be able to fold alone the line of symmetry so that the two parts are mirror images of each other. The folded line would be the line of symmetry. An image that is symmetrical would have a line of symmetry such as a square (four lines of symmetry), a circle (infinite lines of symmetry) or a butterfly (one line of symmetry).
    ::图像要具有对称线, 图像必须能够单独折叠对称线, 使两部分成为彼此的镜像。 折叠线将是对称线。 对称线的图像将具有对称线, 如方形( 四行对称 ) 、 圆形( 无限对称线) 或蝴蝶( 一行对称 ) 。

    Example 2
    ::例2

    Does this figure have symmetry? Can it be a reflection ?
    ::这个数字是否对称?它能是一个反射吗?

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    First, try to divide this butterfly evenly so that one side can reflect the other. Can you draw a line of symmetry?
    ::首先,试着将蝴蝶平均地分开,这样一面就能反射到另一边。你能画出对称线吗?

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    The answer is yes.
    ::答案是肯定的。

    Therefore, it has symmetry.
    ::因此,它具有对称性。

    Example 3
    ::例3

    Does the figure below have symmetry? Can it be a reflection?
    ::下图是否具有对称性?它是否是一种反射?

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    First, try to divide this flower evenly so that one side can reflect the other. Can you draw a line of symmetry?
    ::首先,试着将花朵平均地分割开来,这样一面就能反射另一面。你能画出对称线吗?

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    The answer is yes.
    ::答案是肯定的。

    Therefore, it has symmetry.
    ::因此,它具有对称性。

    Example 4
    ::例4

    How many lines of symmetry does this figure have?
    ::这个数字有多少对称线?

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    First, try to divide this rectangle evenly so that one side can reflect the other. Can you draw a line of symmetry?
    ::首先,试图将矩形平分,这样一面就能反射到另一边。你能画出对称线吗?

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    The answer is yes. Therefore, a rectangle has two lines of symmetry.
    ::答案是肯定的。因此,矩形有两条对称线。

    Example 5
    ::例5

    Do these figures have symmetry?
    ::这些数字是否对称?

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    First, try to divide these images evenly so that one side can reflect the other. Can you draw a line of symmetry for any of these images?
    ::首先, 试着将这些图像平均分隔, 这样一面可以反射另一面 。 您能够为这些图像中的任何图像绘制一条对称线吗 ?

    The answer is no.
    ::答案是否定的。

    Therefore, none of these images have a line of symmetry.
    ::因此,这些图象没有一个对称线。

    Review
    ::回顾

    Use the illustration to answer each question.
    ::用插图回答每个问题。

    lesson content

    1. Does this figures have lines of symmetry?
    ::1. 这些数字是否对称?

    3. How many lines of symmetry does the figure have?
    ::3. 数字有多少对称线?

    Find all lines of symmetry for the shapes below.
    ::查找下方形状的所有对称行 。

    4. 

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    5. L
    ::5. L

    6. T
    ::6.T 6T

    Name the number of lines of symmetry for each letter.
    ::每个字母的对称行数 。

    7. E
    ::7. E

    8. A
    ::8. A 级

    9. M
    ::9. M 级

    10. G
    ::10. G级

    11. H
    ::11. H 11 H

    Answer each question true or false.
    ::回答每个问题是否真实或虚假。

    12. All triangles have symmetry.
    ::12. 所有三角都有对称性。

    13. All circles have symmetry.
    ::13. 所有圆圈都有对称性。

    14. The letter “X” has two lines of symmetry.
    ::14. " X " 字母有两行对称。

    15. The letter “S” has two lines of symmetry.
    ::15. " S " 字母有两行对称。

    Review (Answers)
    ::回顾(答复)

    Click to see the answer key or go to the Table of Contents and click on the Answer Key under the 'Other Versions' option.
    ::单击可查看答题键, 或转到目录中, 单击“ 其他版本” 选项下的答题键 。

     

    Resources
    ::资源