Using Pythagorean theorem we can easily get to know about the triangle.
If c^2=a^2 + b^2 Then triangle is Right Angled.
If c^2 > a^2 + b^2 Then triangle is obtuse triangle
and when c^2 < a^2 + b^2 , it means triangle is acute triangle.
( Here a= adjacent, b= opposite and c=hypotenuse of triangle)