Solve the following :

Question:
Suppose $\mathrm{A}$ and $\mathrm{B}$ in the previous problem change their positions in such a way that the line joining them becomes perpendicular to the direction of wind while maintaining the separation $x$. What will be the time lad $B$ finds between seeing and hearing the drum beating by $A$ ?

Solution:

Let $v$ be the velocity of sound along direction $A C$ so it can reach $B$ with resultant velocity $A D$