If the measures of the sides of triangle are $$(x ^{2} - 1), (x^{2} + 1)$$ and 2x cm, then the triangle would be

Sides of the triangle are = $$(x ^{2} - 1), (x^{2} + 1)$$ and $$2x$$

By putting $$x$$ = 2, we get the sides as 3,4,5 which are the sides of right angled triangle.Thus, we need to check for only right angled triangle

Clearly, longest side here is $$(x^2+1)$$

=> $$[(x^2-1)^2 + (2x)^2]$$ = $$(x^4 + 1 - 2x^2 + 4x^2)$$

= $$(x^4 + 2x^2 + 1)$$

= $$(x^2 + 1)^2$$

Thus, these are the sides of a right angled triangle.