Final answer:
The distance between points B and B' remains the same after reflections, meaning the initial distance is the answer no matter how many reflections occur.
Step-by-step explanation:
The question asks for the distance between points B and B' after two reflections to form triangles ∆ABC and ∆A'B'C'. During a reflection across a line, the distance between a point and its image remains constant. That means, with each reflection, point B moves to B' but the distance between them does not change. If B is reflected to B' across one line, then across another line to form B'', the distance between B and B' or B' and B'' would be the same after each reflection. Therefore, the distance between B and B' after any number of reflections is unchanged from its original value.
Learn more about Reflection in Geometry