Puzzle 46 Solution

After drawing the smallest box with the 3 circles, work out the angles as shown above. Looking at the VERTICAL dotted line, we can see that the side length of the square is equal to the length of the vertical dotted line and the length of 2 radii of the circles.

The vertical dotted line is given by 10cos15. 2 radii form a diameter. So the side length of the square is: 10cos15 + 10 = 19.66 to the nearest cm.

Answer: 19.66