Using the information that ∠B ≅ ∠C,
we need to demonstrate that sides AB and AC are equal.
This can be shown using a proof by contradiction.
Assume for the sake of argument that AB
is not equal to AC.
This means either AB > AC or AB < AC.
Case i: If AB > AC, then according to the triangle axiom, Angle C must be greater than angle B.
However, given that Angle C = Angle B, we see that AB cannot be greater than AC.
Case ii: If AB < AC, then by the triangle axiom, Angle C would have to be less than angle B.
Since Angle C = Angle B, we conclude that AB cannot be less than AC either.
Conclusion:
Therefore, since AB cannot be either greater than or less than AC, we are left with only one possibility, which is that AB = AC.
Thus, from the fact that angle B equals angle C, we deduce that
AB = AC, and AB ≅ AC.