Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
3. Rotations
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Exercise 33 Page 62

Perform the transformations in different orders and check when we end at the treasure.

Example Solution:

  • Rotate by 180^(∘) about the origin.
  • Rotate by 90^(∘) counterclockwise about the origin.
  • Reflect in the y-axis.
  • Translate 1 unit right and 1 unit up.
Practice makes perfect

Let's take a look at the given diagram.

treasure map

It shows a green point ( ∙) and a red X ( *) on the coordinate plane. The ( ∙) is our position and the ( *) is the position of the treasure. We can find this treasure by performing the following four transformations in a correct order.

  • Rotate 180^(∘) about the origin.
  • Reflect in the y-axis.
  • Rotate 90^(∘) counterclockwise about the origin.
  • Translate 1 unit right and 1 unit up.

    These transformations are not in the correct order but let's assign each of them a number. Then we can call each transformation by its number without writing down the whole transformation.

    1. Rotate 180^(∘) about the origin.
    2. Reflect in the y-axis.
    3. Rotate 90^(∘) counterclockwise about the origin.
    4. Translate 1 unit right and 1 unit up.
    Now, let's try to use our transformations to move the ( ∙) to the ( *).
    Diagram with the transformations
    When we tried enough combinations, we found that the following order works!
    Number Transformation
    1. Rotate 180^(∘) about the origin.
    3. Rotate 90^(∘) counterclockwise about the origin.
    2. Rotate in the y-axis.
    4. Translate 1 unit right and 1 unit up.
    However, it is not the only solution. We can see some other orders that allow us to find the treasure! 1 → 3 → 2 → 4 [0.5em] 3 → 1 → 2 → 4 [0.5em] 1 → 4 → 3 → 2 [0.5em] 3 → 2 → 1 → 4 We can check that this is the case.
    Diagram with the transformations