What is more preferrable way to say length is 1?

Question

I was wondering which of the following is more preferrable:

Let $ABC$ be an equilateral triangle with $AB=1$.

or

Let $ABC$ be an equilateral triangle with $|AB|=1$?

And should I use the character | or \mid when I write that formula in LaTeX?

Answer 1

Generally speaking, we say this: Let $ABC$ be an equilateral triangle with $|AB|=1$.

The character | or \mid is noth Okay.