Prove that (BD)/(AC) = (DR)/(AQ) given AB = AC and PQ = PR.

Part (a):
Given: $AB = AC$ and $PQ = PR$.
Prove: $\frac{BD}{AC} = \frac{DR}{AQ}$.

Step 1: Identify equal angles from the given information.
Since $AB = AC$, $\triangle ABC$ is an isosceles triangle. Therefore, the base angles are equal:

$$\angle ABC = \angle ACB$$

Let $\angle ABC = \angle ACB = \beta$.

Since $PQ = PR$, $\triangle PQR$ is an isosceles triangle. Therefore, the base angles are equal:

$$\angle PQR = \angle PRQ$$

Let $\angle PQR = \angle PRQ = \alpha$.
Note that $\angle PQR$ is the same as