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Big Ideas Math Integrated I, 2016

BI

Big Ideas Math Integrated I, 2016 View details

3. Rotations

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Exercise 19 Page 567

Rotational symmetry means that you can spin the figure 180^(∘) or less so that it maps onto itself.

Yes, 45^(∘), 90^(∘), 135^(∘), and 180^(∘).

Practice makes perfect

If we draw segments from the tip of the sun's rays and to the middle of the circle, we create 8 congruent angles like below.

Since a circle is 360^(∘), we know that each angle has to be 360^(∘)/8=45^(∘). Therefore, if we rotate the sun by 45^(∘), it will map onto itself.

The image will also map onto itself it we rotate it 90^(∘), 135^(∘), and 180^(∘).

Subchapter links

Communicate Your Answer p.561

Monitoring Progress p.563-565

Exercises p.566-568