In this chapter we will look at the concept of reflection symmetry with properties and examples.
What is Reflection symmetry ?
Reflection symmetry is also known as line symmetry or mirror symmetry in geometry.
In reflection symmetry, a reflection image is formed across the axis of symmetry.
Hence in reflection symmetry, one part of image is the mirror image of another.
Note the image of car above.
The yellow line MN is called the line of symmetry.
Note that the right part of the image is the reflection of left part separated by axis line MN.
English letter ” A “
Here the red line MN is axis of symmetry.
The right part of alphabet is the mirror image of the left part.
Given above is the object and its mirror image separated by line of symmetry MN.
What is Line of symmetry ?
Line of symmetry is the axis around which the mirror image form.
There can be different lines of symmetry;
(a) Horizontal line of symmetry
(b) Vertical line of symmetry
(c) Diagonal line of symmetry
Let us understand each of the above in detail.
Horizontal line of symmetry
The horizontal line around which the mirror image is formed is called horizontal line of symmetry.
Given above is the object and mirror image across the horizontal line of symmetry MN.
Vertical line of symmetry
The vertical line across which the reflection forms is called Vertical line of symmetry.
Given above is the object ” CROSS ” and its reflection image.
Note that it’s the vertical axis PQ across which the reflection forms.
Diagonal line of Symmetry
A tilted straight line across which reflection occurs is called diagonal line of symmetry.
Given above is the square ABCD and MN is the diagonal axis of symmetry across which reflection images formed.