contestada

Given that AD is the perpendicular bisector of BC, AB=21.3, AC=21.3, and DC=9.1, identify BC.

a) BC = 42.6
b) BC = 18.2
c) BC = 9.1
d) BC = 4.55

sorry i can't upload a picture of the triangle but this is from an luoa assignment. i know it's not C