The sides form a pythagorian triplet because the sum of square of 2 sides ( a and √2a) is equal to the square of the third side (i.e. √3a)
Thus, triangle is a right angled triangle. This means the greatest angle is 90 degree.
We know that, in a triangle, the greatest angle lies opposite to the greatest side.
Thus, the angle opposite to greatest side will be 90 degrees