From the given pattern, it can be observed that,

(i) The third number is the product of the first two numbers.

(ii) The fourth number can be obtained by adding 1 to the third number.

Thus, the missing numbers in the pattern will be as follows.

4^{2} + 5^{2} + **20**^{2} = 21^{2}

5^{2} + **6**^{2}+ 30^{2} = 31^{2}

6^{2} + 70 + **42**^{2} = **43**^{2}