Given that the lengths of three sides of a triangle a, B, C satisfy a & # 178; + B & # 178; + C & # 178; - AB BC AC = 0, try to judge the shape of the triangle

Given that the lengths of three sides of a triangle a, B, C satisfy a & # 178; + B & # 178; + C & # 178; - AB BC AC = 0, try to judge the shape of the triangle

∵a²+b²+c²-ab-bc-ac=0
∴2a²+2b²+2c²-2ab-2bc-2ac=0
∴(a-b)²+(b-c)²+(c-a)²=0
A-B = 0 and B-C = 0 and C-A = 0
∴a=b=c
Equilateral triangle