What if you you had a six-pointed star and you rotated that star less than ? If the rotated star looked exactly the same as the original star, what would that say about the star? After completing this Concept, you'll be able to determine if a figure like this one has rotational symmetry.
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Guidance
Rotational symmetry is present when a figure can be rotated (less than ) such that it looks like it did before the rotation. The center of rotation is the point a figure is rotated around such that the rotational symmetry holds.
For the , we can rotate it twice, the triangle can be rotated 3 times and still look the same and the hexagon can be rotated 6 times.
Example A
Determine if the figure below has rotational symmetry. Find the angle and how many times it can be rotated.
The pentagon can be rotated 5 times. Because there are 5 lines of rotational symmetry, the angle would be .
Example B
Determine if the figure below has rotational symmetry. Find the angle and how many times it can be rotated.
The can be rotated twice. This means the angle of rotation is .
Example C
Determine if the figure below has rotational symmetry. Find the angle and how many times it can be rotated.
The checkerboard can be rotated 4 times. There are 4 lines of rotational symmetry, so the angle of rotation is .
Guided Practice
Find the angle of rotation and the number of times each figure can rotate.
1.
2.
3.
Answers:
1. The parallelogram can be rotated twice. The angle of rotation is .
2. The hexagon can be rotated six times. The angle of rotation is .
3. This figure can be rotated four times. The angle of rotation is .
Practice
- If a figure has 3 lines of rotational symmetry, it can be rotated _______ times.
- If a figure can be rotated 6 times, it has _______ lines of rotational symmetry.
- If a figure can be rotated times, it has _______ lines of rotational symmetry.
- To find the angle of rotation, divide by the total number of _____________.
- Every square has an angle of rotation of _________.
Determine whether each statement is true or false.
- Every parallelogram has rotational symmetry.
- Every figure that has line symmetry also has rotational symmetry.
Determine whether the words below have rotation symmetry.
- OHIO
- MOW
- WOW
- KICK
- pod
Find the angle of rotation and the number of times each figure can rotate.
Determine if the figures below have rotation symmetry. Identify the angle of rotation.