If the three sides of a triangle A.B.C satisfy that the square of a plus the square of B plus the square of C equals AB plus AC plus BC, try to determine the shape of the triangle

If the three sides of a triangle A.B.C satisfy that the square of a plus the square of B plus the square of C equals AB plus AC plus BC, try to determine the shape of the triangle

Equilateral triangle=
Deform the equation``
(a-b)^2+(b-c)^2+(c-a)^2=0
So a = b = C