It is a right triangle if it satisfies the pythagorean theorem:
[tex]\begin{gathered} c^2=a^2+b^2 \\ \text{where:} \\ c>a \\ c>b \\ so\colon \\ a=3 \\ b=4 \\ c=5 \\ 5^2=3^2+4^2 \\ 25=9+16 \\ 25=25 \\ \text{Which is true} \end{gathered}[/tex]Therefore, it is a right triangle
