Let a, b and c represent the 3 sides of a traingle
If c^2 < a^2 + b^2, the triangle is acute
If c^2 > a^2 + b^2, the triangle is obtuse
If c^2 = a^2 + b^2, the triangle is a right angle triangle
If a = 5, b = 12 and c = 13, then
13^2 = 5^2 + 12^2, then it is a right angle triangle
If a = 5, b = 9 and c = 13, then
5^2 + 9^2 < 13^2, then it is an acute triangle
If a = 9, b = 12 and c = 13, then
9^2 + 12^2 > 13^2, then it is an obtuse triangle
