Two persons A and B travelling at `60 km//hr^(–1)` in their cars moving in opposite directions on a straight road observe an airplane. To the person A, the airplane appears to be moving perpendicular to the road while to the observe B the plane appears to cross the road making an angle of `45°`.
(a) At what angle does the plane actually cross the road (relative to the ground).
(b) Find the speed of the plane relative to the ground.

Answer

(a) `theta = tan^(-) (2)` (b) `60 sqrt(5) kmhr^(-1)`