Problem 6 has a similar resolution too: you have the circle of radius sqrt(3) and the rect a+b=n^2. Considering the fact that n is natural is easy to find the

Problem 6 has a similar resolution too: you have the circle of radius sqrt(3) and the rect a+b=n^2. Considering the fact that n is natural is easy to find the solutions: n=0 and n=1