Question

PLEASE HELP! Since AB=1 and 1=BC, BC=AB by which property?

Answer 1

Substitution.

Here is an example.

Let x be equal to 3 and y equal to 3.

$x=3, y=3$

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

$x\wedge y=3\Longrightarrow x=y$

Here in your case we have:

$AB=1, BC=1 \\AB\wedge BC=1\Longrightarrow AB=BC$

Hope this helps.

r3t40