Lesson Objective

This lesson shows you the ideas behind 2D
Rotational Symmetry. Also, you will get to see a
quick video demonstration on it.

About This Lesson

When we rotate a shape about its center point,
we may notice that at a certain angle, the
rotated shape coincides with its 'not rotated'
self (see picture).

When this happens, the shape is said to has rotational symmetry. This lesson will show the ideas behind it.

You can proceed by reading the study tips first or watch the math video or try out the practice questions.

When this happens, the shape is said to has rotational symmetry. This lesson will show the ideas behind it.

You can proceed by reading the study tips first or watch the math video or try out the practice questions.

Tip #1

When we rotate the triangle about its center point for
360^{o}, we notice that it fits onto
itself for 3 times for every 120^{o} rotation.

By definition, the number of times a shape fits onto itself when rotated is called the*order of symmetry*.

Hence, we can see that the order of symmetry for this triangle is 3.

The math video below will show you more on this visually.

By definition, the number of times a shape fits onto itself when rotated is called the

Hence, we can see that the order of symmetry for this triangle is 3.

The math video below will show you more on this visually.

Tip #2

Now, this shape only fits onto itself
1 time after rotate for 360^{o}. Hence, the order of symmetry is 1.

However, for any shape that has rotation symmetry of**order 1**, that shape is considered as **not** having any
rotational symmetry.

Hence, this shape has no rotational symmetry.

However, for any shape that has rotation symmetry of

Hence, this shape has no rotational symmetry.

Multiple Choice Questions (MCQ)

Now, let's try some MCQ questions to understand
this lesson better.

You can start by going through the series of questions on 2d rotational symmetry or pick your choice of question below.

You can start by going through the series of questions on 2d rotational symmetry or pick your choice of question below.

- Question 1 on rotational and order of symmetry