Final answer:
Coordinates of B that show MC bisects side AB at its midpoint would prove MC is a median of triangle ABC, especially in an isosceles triangle where AB = BC.
Step-by-step explanation:
In order for MC to be considered a median of △ABC, it must connect vertex C to the midpoint of side AB. This means that B must have coordinates that allow MC to bisect AB. In a triangle with sides AB = BC, which indicates an isosceles triangle, the midpoint of AB would lie exactly halfway between A and B. Verifying that the coordinates of point B result in MC intersecting the midpoint of AB would provide the necessary proof that MC is a median of △ABC.
If AB = BC = r, indicating an isosceles triangle, the coordinates of B must uphold this relationship. With further geometric properties considered, such as perpendicular baselines and angles of incidence as mentioned, one should ensure that all the parameters are satisfied to prove that MC is indeed a median. In summary, the coordinates of B must align with MC bisecting AB at its midpoint for MC to be validated as a median.