i got to classify if its a acute or obtuse or right and justify my answer

The triangle is an obtuse triangle if the sum of the squares of the smaller sides is less than the square of the largest side. The square of the longest side is less than the sum of the squares of two smaller sides.
So here,
[tex]\begin{gathered} 8.6^2=73.96 \\ 5.3^2=28.09 \\ 3.2^2=10.24 \\ 10.24+28.09=38.33 \end{gathered}[/tex]Therefore, we have,
[tex]3.2^2+5.3^2<8.6^2[/tex].Thus, the triangle is obtuse.