In the triangle ABC, A4 + B4 + C4 + a2b2-2a2c2-2b2c2 = 0, then the angle C=

In the triangle ABC, A4 + B4 + C4 + a2b2-2a2c2-2b2c2 = 0, then the angle C=

Sort out this formula
(b2-c2) 2 + A2 (A2 + b2-2c2) = 0
It can be seen that the parts on both sides of the plus sign can not be positive and negative, because the square of the constant is equal to or greater than 0, and both sides are equal to 0, that is, b2-c2 = 0, A2 (A2 + b2-2c2) = 0
The first formula gives B = C
The second formula a ≠ 0, so A2 + b2-2c2 = 0, because B = C, so A2 + b2-2b2 = 0, that is, a = B
The triangle is equilateral and the angle c is 60