A plane is flying at 140km/h in a wind blowing 60km/h (S20*E) in which direction should the plane fly to go 1000km directly North? How long will it take?




Help me I'm lost!! :

It will be easy if you tell me what is meant by (S20*E).

It seems you mean 20 degrees south of East. (MODIFY THE FOLLOWING IF YOU MEAN SOMETHING ELSE)

If this is correct, draw a triangle ABC with one side AC = 60, going 20 degrees south of east, AB Vertically upward and CB = 140

Angle CAB = 90 + 20 = 110

By Sine rule, solve

140/Sin 110 = 60 /Sin B

This will give you value of B, CB is the direction for aeroplane to travel.

(Wind takes you from A to C, aeroplane goes along CB, Result: AB)


Angle C = 180 - (A + B)

This will give you angle C
Again by Sine rule:

AB / Sin C = 140/Sin 110

This gives you value of AB, the resultant velocity vertically upward

Time taken = 1000/AB