Question 134
Given $\triangle ABC$ and $\triangle AEF$ such that $B$ is the midpoint of $EF$. Also, $AB = EF = 1$, $BC = 6$, $CA = \sqrt{33}$, and $\overrightarrow{AB} \cdot \overrightarrow{AE} + \overrightarrow{AC} \cdot \overrightarrow{AF} = 2$. The cosine of the angle between $\overrightarrow{EF}$ and $\overrightarrow{BC}$ is ______.