A line of symmetry divides a two-dimensional figure into two congruent mirror-image parts: corresponding points lie the same perpendicular distance from the line on opposite sides. Learners identify all lines of symmetry in familiar shapes and drawings, including vertical, horizontal, and diagonal lines, understanding that apparent visual balance alone is insufficient. The focus is on pictorial figures rather than coordinate rules, formal transformations, or advanced classifications of symmetry.
A line of symmetry is a line that splits a figure into two matching mirror-image parts.
Imagine folding the figure along the line:
Find all the lines of symmetry in a square.
Draw a vertical line through the center.
The left half folds onto the right half exactly.
So, this is a line of symmetry.
Draw a horizontal line through the center.
The top half folds onto the bottom half exactly.
So, this is another line of symmetry.
Draw a diagonal from the top-left corner to the bottom-right corner.
The two triangular halves match when folded.
So, this is a line of symmetry.
Draw the other diagonal, from the top-right corner to the bottom-left corner.
These two triangular halves also match when folded.
So, this is a line of symmetry.
Therefore, a square has 4 lines of symmetry:
Always check whether the parts would match as mirror images. A figure may look balanced, but that alone does not prove that a line is a line of symmetry.
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