Question

12,5,13 form a Pythagorean triplet

Answer 1

hyp sq. =side sq. +side sq.
13 sq. =12 sq. +5 sq.
169=144+25=169
Therefore proved

Answer 2

(hyp)^2=(adj)^2+(opp)^2
(13)^2=(12)^2+(5)^2
169=144+25
169=169