Line of Symmetry
Definition of Line of Symmetry
Line of symmetry is a line that divides a figure into two congruent parts, each of which is the mirror images of the other.
When the figure having a line of symmetry is folded along the line of symmetry, the two parts should coincide.
Video Examples: Identify Lines of Symmetry
Example of Line of Symmetry

The dotted line shown in the figure is the Line of Symmetry.
Solved Example on Line of Symmetry
Ques: Among the dotted lines in the figures, which one is a line of symmetry?
Choices:
A. the dotted lines in Figure 2B. the dotted lines in Figure 3
C. the dotted lines in Figure 1
D. the dotted lines in Figure 4
Correct Answer: A
Solution:

Step 1: Line of Symmetry is a line that divides the figure into two parts, which are mirror image of each other.
Step 2: Among the choices, the dotted line through the letter M divides it into two parts, which are mirror image of each other.
Step 3: The lines passing through the letters L, P, and Q do not divide them into two parts that would be mirror images of each other.
Step 4: So, the dotted line through the letter M is a line of symmetry.
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