find the missing numbers. 1^2 + 2^2 + 2^2 = 3^2 2^2 + 3^2 + 6^2 = 7^2 3^2 + 4^2 + 12^2 = 13^2 4^2 + 5^2 + _^2 = 21^2 5^2 + _^2 + 30^2 = 31^2 6^2 + 7^2 + _ ^2 = _ ^2