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Lesson 6: Line of symmetry

# Symmetry review

Review symmetrical shapes and lines of symmetry.  Then, try some practice problems.

## Line of symmetry

A $\text{line of symmetry}$ is a line where we can fold the image and have both halves match exactly.
Example:
When we divide the figure with Line $A$, the resulting two parts are mirror images of each other:
Line $A$ is a line of symmetry.

## Symmetrical figures

Shapes are $\text{symmetrical}$ if they have at least one $\text{line of symmetry}$ on them.
Example:
This shape is $\text{symmetrical}$:
Because we can draw at least one $\text{line of symmetry}$ on it:

## Practice

Problem 1
In the figure below, which of the following is a line of symmetry?

## Want to join the conversation?

• How many lines of symmetry does a circle have
• Circles have an infinite amount of lines of symmetry. You can go on and on and on and never find a specific number of lines of symmetry. Circles are the only figures that have an infinite amount of lines of symmetry.
• how many lines of symmetry does a circle have
• A circle has infinite lines of symmetry
• I did not understand how the pentagon had symmetry that way can you help me please?
• Yes, if you fold the pentagon over the dotted line, then the two pieces would match perfectly.
• how to find total number of lines of symmetry
• just do it as many times and many ways till you get all you need
• so the amount of sides there is in the shape is how much lines of symmetry there is in that shape
• Symmetry is basically two sides of a shape that are the same. Imagine a triangle split in half. That would be symmetrical. Good luck and keep practicing!
• how do you solve decomposing angles when there is no sign of solving it. it is impossible when you have to subtract the numbers and then the answer is wrong, i never get the decomposing angle questions right, i always get 0% in them. geometry is difficult. isn't it. i always try to solve the questions if they are not right, but it never is right and i never get them right even after having a second go at them.
• Every body can make mistakes just keep trying
• whats the meaning of life