A boy is riding a cycle with a speed of $5\sqrt3$m/s towards east along a straight line.It starts raining with a speed of 15m/s in the vertical direction.What is the direction of rainfall as seen by the boy.

Question

$\begin{array}{1 1}30^{\large\circ}\\20^{\large\circ}\\10^{\large\circ}\\50^{\large\circ}\end{array}$