It is an acute triangle, because the following characterization holds:
- If [tex]c^2<a^2+b^2[/tex], the triangle is acute
- If [tex]c^2=a^2+b^2[/tex], the triangle is right
- If [tex]c^2>a^2+b^2[/tex], the triangle is obtuse
In this case,
[tex]6^2=36<5^2+4^2=25+16=41[/tex]
