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    ::[图1]

    Harwin lives at the corner of a street. His street ends and another street begins at the corner. He sees the two streets on a map of the area and notices that his corner looks like the following figure. 
    ::Harwin住在街角,他的街尾和另一条街从街角开始,他看到两条街的地图上,注意到他的街角像下图。

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    What is the measure (in degrees) of the angle formed by his street and the other street?
    ::衡量他的街道和另一条街道所形成的角度(度)的尺度是什么?

    In this concept, you will learn about angle measurements.

    ::在这个概念中,你会学习角度测量。

    Measuring Angles
    ::测量角度

    Angles are measured in  degrees . The larger the angle, the higher the number of degrees.
    ::角度以度计量。角度越大,度数越高。

    Angles are measured using a special tool called a  protractor .
    ::使用称为减速器的特殊工具测量角。

    Here is a picture of a protractor.
    ::这是一张减速器的照片。

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    Notice that you can see all of the degrees on the protractor.
    ::注意你可以看到 减速器上的所有度

    Here are the steps for using a protractor.
    ::以下是使用减速器的步骤。

    1. First, you line up the vertex with the little hole in the middle of the protractor, then carefully align the bottom ray with the bottom line of the protractor.
      ::首先,你把顶部排成一排, 在减速器中间有个小洞, 然后仔细地将底线与减速器底线对齐。
    2. Then, you follow the top ray to the number of degrees that the angle measures.
      ::然后,你沿着上面的光线 向上到角度测量的度数。

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

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    Use a protractor to measure this angle.
    ::使用减量器测量此角度 。

    First, line up your protractor to measure. Be sure that the vertex is at 0. Then write down each number of degrees.
    ::首先, 排队测量您的减速器。 请确定顶点为 0 。 然后写下每一度数 。

    120 degrees
    ::120度 120度

    Examples
    ::实例

    Example 1
    ::例1

    Earlier, you were given a problem about Harwin and his street corner.
    ::早些时候,你得到一个问题 关于哈温和他的街角。

    His street corner looks like the following figure.
    ::他的街角看起来像下图

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    What is the measure (in degrees) of the angle formed by his street and the other street?
    ::衡量他的街道和另一条街道所形成的角度(度)的尺度是什么?

    First, line up the hole in the middle of the protractor with the vertex.
    ::首先,在减速器中间的洞里用脊椎排成一列

    Next, align the bottom ray with the bottom line of the protractor.
    ::接下来,将底线与减速器的底线对齐。

    Then, follow the other ray and draw a line up to the angle measure.
    ::然后沿着另一条射线 画一条直线到角度

    90 degrees
    ::90度 90度

    The answer is 90 degrees.
    ::答案是90摄氏度

    Example 2
    ::例2

    Is this angle larger than 90 degrees?
    ::这个角度大于90度吗?

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    First, line up the hole in the middle of the protractor with the vertex and align the bottom ray with the bottom line of the protractor.
    ::首先,将减速器中间的洞与顶点排成一行,并将底线与减速器底线对齐。

    Next, look at the angle measure
    ::下一步, 看看角度度量

    120

    Then, determine if that number is larger than 90 degrees.
    ::然后,确定这个数字是否大于90度。

    Yes
    ::是 是

    The answer is that this angle is larger than 90 degrees.
    ::答案是这个角度大于90度

    Example 3
    ::例3

    How many degrees are in a straight line?
    ::直线有多少度?

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    First, line up the hole in the middle of the protractor with the vertex and align the bottom ray with the bottom line of the protractor.
    ::首先,将减速器中间的洞与顶点排成一行,并将底线与减速器底线对齐。

    Next, follow the other ray to the angle measure.
    ::接下来,沿着另一射线到角度。

    Then, write the angle measure.
    ::然后,写下角度量度。

    180 degrees
    ::180度 180度

    The answer is 180 degrees.
    ::答案是180摄氏度

    Example 4
    ::例4

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    How would you use a protractor to determine the measure of this angle?
    ::您将如何使用减量器来确定这个角度的量度 ?

    First, line up the hole in the middle of the protractor with the vertex.
    ::首先,在减速器中间的洞里用脊椎排成一列

    Next, align the bottom ray with the bottom line of the protractor.
    ::接下来,将底线与减速器的底线对齐。

    Then, follow the other ray and draw a line up to the angle measure.
    ::然后沿着另一条射线 画一条直线到角度

    The answer is to follow the other ray and draw a line up to the angle measure.
    ::答案是跟随另一个射线,在角度测量上绘制一条线。

    Example 5
    ::例5

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    What is the measure of this angle?
    ::这个角度的量度是多少?

    First, line up the hole in the middle of the protractor with the vertex.
    ::首先,在减速器中间的洞里用脊椎排成一列

    Next, align the bottom ray with the bottom line of the protractor.
    ::接下来,将底线与减速器的底线对齐。

    Then, follow the other ray and draw a line up to the angle measure.
    ::然后沿着另一条射线 画一条直线到角度

    35 degrees
    ::35度 35度

    The answer is 35 degrees.

    ::答案是35摄氏度

    Review
    ::回顾

    Draw the following angles. Be sure to use a protractor and check your work with a friend.
    ::绘制以下角度。 请确定使用减号, 并检查您与朋友的工作 。

    1. 180 degrees
      ::180度 180度
    2. 100 degrees
      ::100度 100度
    3. 90 degrees
      ::90度 90度
    4. 15 degrees
      ::15度 15度
    5. 20 degrees
      ::20度 20度
    6. 45 degrees
      ::45度 45度
    7. 60 degrees
      ::60度 60度
    8. 110 degrees
      ::110度 110度
    9. 25 degrees
      ::25度 25度
    10. 160 degrees
      ::160度 160度
    11. 180 degrees
      ::180度 180度
    12. 140 degrees
      ::140度 140度
    13. 42 degrees
      ::42度 42度
    14. 115 degrees
      ::115度 115度
    15. 173 degrees
      ::173度

    Review (Answers) 
    ::回顾(答复)