Question #080f7

1 Answer
Feb 20, 2017

drawn

From starting position O the bearing of current is 345^@ and that of direction of destination is 100^@. So the angle between the direction of current and the direction of destination is (360-345+100)^@=115^@

Again the ship is to cover 700km in 20hr to reach at the destination

So its velocity along the direction of destination OD is

V_d=700/20=35"km/h"

The velocity of current along OC

is V_c=5"km/h"

Le the velocity of ship along OE will be V_s and this velocity makes an angle alpha with OD.

Considering cosine law for triangle ODE we can write

V_s^2=V_c^2+V_d^2-2V_cV_dcos115

=>V_s^2=5^2+35^2-2*5*35cos115

V_s=37.4"km/h"

Now applying sin law for triangle ODE we get

V_d/sin115=5/sinalpha

=>37.4/sin115=5/sinalpha

=>sinalpha=5/37.4xxsin115~~0.12

=>alpha~~7^@

So the bearing of the direction of the ship to be driven is 107^@