Answer:
Speed of Plane A Which left Station O at 1:00 pm= 575 mph bearing N 27°E
Speed of Plane B Which left Station O at 1:45 pm= 625 mph bearing W 65° S
Taking resolution of plane A and B along X axis
Speed of plane A along X axis =575 cos 27°=575× 0.891=512.325 mph
Speed of Plane B along X axis= 625 cos 65°= 625× 0.422=263.75 mph
After 3.5 hours, Distance traveled by plane A i. e till 4:30 P.M =512.325× 7/2 = 1793.1375 miles → along positive X axis i.e from point O.
After 3.5 hours, Distance traveled by plane B i. e till 5:15 P.M=263.75 × 7/2 = 923.125 miles →along negative X axis i.e from point O.
The two planes are apart by a distance =1793.1375 - ( -923.125)
=1793.1375 + 923.125
= 2716.2625 miles