For any natural number m, we have 2m, m2 – 1, m2 + 1 is a Pythagorean triplet.
(i) Consider 2m = 16 ⇒ m = 8
m2 – 1 = 64 – 1 = 63
m2 + 1 = 64 + 1 = 65
So Pythagorean triplet is 16, 63, 65.
(ii) Consider 2m = 18 ⇒ m = 9
m2 – 1 = 81 – 1 = 80
m2 + 1 = 81 + 1 = 82
So Pythagorean triplet is 18, 80, 82.