If ABC is known to be the trilateral length of △ ABC and the absolute value of A-B plus the absolute value of B-C = 0, then ABC is a triangle

If ABC is known to be the trilateral length of △ ABC and the absolute value of A-B plus the absolute value of B-C = 0, then ABC is a triangle

│a-b│+│b-c│=0
A-B = 0 and B-C = 0
a=b=c
This is an equilateral triangle