Solution: Which is Bigger?

The Puzzle:

In the picture, is the area coloured green or the area coloured blue bigger?

The Solution:

Let's draw grid-lines over the puzzle so that it's easier to calculate the areas:

The area of the square is \(10 \times 10 = 100 \text{ square units}\).

The green areas are equivalent to the area of two circles of radius \(3\). So,

Note: If I'd made the green circles just a big smaller, the blue area would have been bigger. For example, if I made the radius \(2.8\), the green area would have been approximately \(47.16 \text{ square units}\), and the blue area would have been \(52.84 \text{ square units}), which is larger.