Finding the Length of BC in Triangle ABC Using the Law of Cosines

In triangle ABC, the lengths of sides AB and AC are given as:

• Side AB = 13 units
• Side AC = 14 units

Additionally, the measure of angle A is $60^{\circ}$. Using the Law of Cosines, determine the length of side BC.

Recall that the Law of Cosines states:

$$c^2 = a^2 + b^2 - 2ab \cdot \cos(C)$$

where $c$ is the side opposite angle $C$, and $a$ and $b$ are the other two sides.