For the sides of triangle sum of two side must greater than other side.
[tex]\begin{gathered} \frac{2}{5}+\frac{4}{5}>\frac{6}{5} \\ \frac{6}{5}\text{ is not greater than }\frac{6}{5} \end{gathered}[/tex]So condition for set to be sides of triangles is not followed. Thus sides does not belong to triangle.
Check for the pythagorean triple.
[tex]\begin{gathered} (\frac{6}{5})^2=(\frac{4}{5})^2+(\frac{2}{5})^2 \\ \frac{36}{25}=\frac{16}{25}+\frac{4}{25} \\ \frac{36}{25}\ne\frac{20}{25} \end{gathered}[/tex]The set does not belongs to right angle triangle.
No it is not a right angle triangle and not form a pythagorean triple.
