Awnser: Side-Angle-Side
Thus is why:
One way to prove that angles B and C are congruent is by proving that triangles BNA and CNA are similar.
We can state that two triangles is similar if:
Side Side Side: If the corresponding sides of both triangles are similar
Angle Angle: If two pairs of angles are congruent
Side Angle Side: If two pairs of sides are similar and 1 pair of angles is congruent in both triangles.
We already know that side AB and AC are congruent.
We can also state that angles BNA and CNA are congruent because it was stated that segment BC is perpendicular to segment AN. ( Theyre both 90°)
Finally both triangles share segment AN, so by the reflexive property if equality, AN = AN
Side AB = Side AC
Angle BNA = Angle CNA
Side AN = side AN
Side angle side
