To prove set A = set B,
we first prove set A is a subset of set B,
and set B is a subet of set A
That means,
- all elements of set A are in set B
- all elements of set B are in set A
Since, both A and B have elements, they are equal
To write it in formula,
We first prove
A ⊂ B
& B ⊂ A
Then, A = B