Mirror, Mirror Puzzle - Solution

The Puzzle:

Mirror, Mirror
If you continue shading the squares so that the two dotted lines become lines of symmetry (mirror lines) of the completed diagram, how many squares will be left unshaded?



Our Solution:

If you continue shading the squares so that the two lines become mirror lines, we get this:



(Note: I have shaded the new squares differently just so that you can see where they go.)

The number of squares left is then 9.
Puzzle Author: Stephen Froggatt

See this puzzle without solution
Discuss this puzzle at the Math is Fun Forum