The Pythagorean triplet whose smallest number 12 is

Pythagorean triplet means square of one side is equal to sum of squares of other two sides 
$$\begin{gathered} {12}^2+{13}^2={15}^2 \\ 144+169=225 \\ \Rightarrow 313=225\text{ (false) } \\ (12,13,15)\text{ is not a Pythagorean triplet } \\ \text{ In }(6,7,8)\text{ smallest number is not }12\text{. } \\ (12,35,37)\Rightarrow {37}^2={35}^2+{12}^2 \\ 1369=1225+144\Rightarrow 1369=1369\text{ (True) } \\ (12,13,14)\Rightarrow {14}^2={12}^2+{13}^2 \\ 196=144+169 \\ 196=313 \left(\mathrm{False}\right) \end{gathered}$$