Finding the Length of Side BC of Triangle ABC

In triangle ABC, the lengths of the sides are such that $AB = 7$ cm, $AC = 24$ cm, and $BC = x$ cm. Triangle ABC satisfies the triangle inequality theorem. Additionally, point D is the midpoint of side BC. If the perimeter of triangle ABC is equal to $48$ cm, what is the length of side BC?

Use the formula for the perimeter of a triangle, which is given by: $$P = AB + AC + BC$$.