Please help me with 11. I do not know why I got it wrong

In the right triangle, there is a relation between the legs of the right angle and the hypotenuse
[tex]a^2+b^2=c^2[/tex]a and b are the legs of the right angle
c is the hypotenuse
Note that the hypotenuse is the longest side in the right triangle
Since the 3 sides are 6, 12, 13, then
6 and 12 are the legs of the right angle
13 is the hypotenuse
By using the relation above
[tex]\begin{gathered} a=6,b=12 \\ a^2+b^2=(6)^2+(12)^2 \\ a^2+b^2=36+144 \\ a^2+b^2=180 \end{gathered}[/tex][tex]\begin{gathered} c=13 \\ c^2=169 \end{gathered}[/tex]The values of them are not equal as the relation above
[tex]a^2+b^2\ne c^2[/tex]Then 6, 12, 13 can not form sides of a right triangle
We disagree
Because the sum of the squares of the smaller sides is not equal to the square of the longest side.