The points  2,3,5,−1,5,−1,4,−3,2forms

Given points areA2,3,5,B−1,5,−1,C4,−3,2The lengths of the sides    AB=9+4+36=49BC=25+64+9=98CA=4+36+9=49         Observing the sides of the triangle, two sides are equal. And square of the one side is sum of squares of other two sides. Therefore, the triangle is right angled isosceles triangle.