Numeracy: finding symmetry in the alphabet

The dotted line through the middle of the letter A is called a mirror line, because if you place a mirror along it, the shape looks exactly the same as the original.

Another name for a mirror line is a line of symmetry. This kind of symmetry can also be called 'reflective symmetry' .

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Symmetry - Regular polygons

If you cut out a rectangle from a piece of paper, and experiment with it and a mirror, you will soon find that it has just two lines of symmetry - one lengthwise and one widthwise.

An equilateral triangle has three lines of symmetry.

Lines of symmetry