What makes a shape symmetrical?

Symmetry

A 2D shape is symmetrical if a line can be drawn through it so that either side of the line looks exactly the same.

The line is called a line of symmetry.

This is sometimes called a 'mirror line' or 'mirror symmetry', because if you put a mirror on the line, the reflection would show the whole shape.

• An isosceles triangle has 1 line of symmetry.

• A square has 4 lines of symmetry.

• A circle has unlimited lines of symmetry!

a line of symmetry drawn on a triangle and square
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