Rotational Symmetry — Worksheet

Rotational Symmetry

Worksheet

Open the Rotational Symmetry module. Set the symmetry number as described in each question, then use the match angles table to answer below.

Name: Date:

Part A: The idea

1. A shape has n-fold rotational symmetry when rotating it by ___ maps it onto itself. 1 pt
  • 360° ÷ n
  • 180°
  • n°
  • 90° ÷ n
2. Set the symmetry number to 5. What is the angle between matches? 1 pt
Answer:
3. The number of times a shape matches itself in a full turn is called the ___ of rotational symmetry. 1 pt

Part B: Using the module

4. Set the symmetry number to 6. What is the angle between matches? 1 pt
Answer:
5. Set the symmetry number to 8. What is the angle between matches? 1 pt
Answer:
6. Set the symmetry number to 3. What is the smallest match angle greater than 0°? 1 pt
Answer:
7. With the symmetry number set to 5, which angle is a match? 1 pt
  • 72°
  • 75°
  • 80°
  • 90°
8. The match angles table always lists 360° as well as 0°. Why? 1 pt
  • 360° is a full turn, so it is the same as 0°.
  • 360° is only listed when the symmetry number is even.
  • It is there to show the table is complete.
  • It is a mistake in the table.

Part C: Reasoning

9. A shape has 6-fold rotational symmetry. Explain why it also lines up after a 120° turn. 2 pts
10. Describe how the match angles change as you increase the symmetry number. Use the table to support your answer. 2 pts