Big Ideas Math: Modeling Real Life, Grade 6
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Big Ideas Math: Modeling Real Life, Grade 6 View details
5. The Coordinate Plane
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Exercise 13 Page 372

To reflect a point in the x-axis, use the same x-coordinate and take the opposite of the y-coordinate. To reflect a point in the y-axis, use the same y-coordinate and take the opposite of the x-coordinate.

(1,-2)

Practice makes perfect

We want to reflect a point in the x-axis and then in the y-axis of a coordinate plane. We need to follow two rules to do this.

  • To reflect a point in the x-axis, we use the same x-coordinate and take the opposite of the y-coordinate.
  • To reflect a point in the y-axis, we use the same y-coordinate and take the opposite of the x-coordinate.
    Point Reflection in the x-axis Reflection in the y-axis
    ( x, y) ( x, - y) ( - x, - y)
    ( -1, 2) ( -1, -2) ( 1, -2)
    As we can see, the reflection of the point is at (1,-2). Let’s plot our point and its reflections on the coordinate plane.
    reflect point
    We can see that the point is located at (1,-2) after both reflections.

    Extra

    More About Coordinate Planes
    A coordinate plane is formed by the intersection of a horizontal number line and a vertical number line. The number lines intersect at the origin and separate the coordinate plane into four regions called quadrants. An ordered pair is used to locate a point in a coordinate plane. The first coordinate represents the x-axis and the second coordinate the y-axis.
    coordinate plane