Question 8
In $\triangle ABC$, $PQ\parallel BC$ where $P$ and $Q$ are points on $AB$ and $AC$ respectively. The lines $PC$ and $QB$ intersect at $G$. It is also given $EF\parallel BC$, where $G\in EF$, $E\in AB$ and $F\in AC$ with $PQ=a$ and $EF=b$. Find value of $BC$.
Editorial clarification: use a nondegenerate triangle and P,Q in the interiors of the stated sides, so the intersection G is well-defined.
Editorial clarification: use a nondegenerate triangle and P,Q in the interiors of the stated sides, so the intersection G is well-defined.