If c is the length of the longest side and a and b are the lengths of the shorter sides, then:
- if \(c^2=a^2+b^2\), the triangle is right
- if \(c^2, the triangle is acute
- if \(c^2>a^2+b^2\), the triangle is obtuse
\(4.2, 6.4, 7.6 \\ \\
a^2+b^2=4.2^2+6.4^2=17.64+40.96=58.6 \\ c^2=7.6^2=57.76 \\ \\
57.76 \ \textless \ 58.6 \\
c^2 \ \textless \ a^2+b^2\)
The triangle is an acute triangle.
