3. In triangle $A B C$, angle $A$ is equal to $60^{\circ}$, the distances from vertices $B$ and $C$ to the center of the inscribed circle of triangle $A B C$ are 3 and 4, respectively. Find the radius of the circle circumscribed around triangle $A B C$.
Answer. $\quad \sqrt{\frac{37}{3}}$. Hint. See problem 4 for 9th grade.