There are certain things which will suffer no alteration, except magnitude, when they grow. If you take a square and add an L-shape to it, the resulting figure is still a square. The portion added is called a ‘gnomon’. A gnomon is any figure which, being added to any figure at all, leaves the resultant figure similar to the original.  For the week that’s in it, I’ve decided to give you Leaving Certificate flashbacks. Imagine an isosceles triangle with one angle of 36 degrees. The other two angles are 72 degrees. Bisect one of the angles at the base. You…