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.
