Page 2 - LN 9.2

What about Figure (b) with the four puzzle pieces and a dotted line passing through the
middle? Are they mirror halves? No, when we fold along the line, the left half does not
exactly fit over the right half. A line that cuts a figure into two parts that exactly overlap
when folded along that line is called a line of symmetry of the figure.

Does a square have only one line of symmetry?
Take a square piece of paper. By folding, find all its lines of symmetry.

Here are the different folds giving different lines of symmetry.

 Fold the paper in half vertically.
 Fold it again into half horizontally. (i.e. you have folded it twice).
 Now open out the folds.

Again fold the square into half (for a third time now), but this time along a diagonal, as
shown in the figure. Again, open it.

Fold it into half (for the fourth time), but this time along the other diagonal, as shown in the
figure. Open out the fold.

We saw that the diagonal of a square is also a line of symmetry.