A boatman wants to reach from one bank of a 2km wide river to a point on another bank , directly oppositeto the point from where he started . If he rows with a speed of 8 km/h , instill water and river flows at the rate of 14km//he, in which direction he should row ?

A boatman wants to reach from one bank of a 2km wide river to a point

1.	A boatman wants to reach from one bank of a 2km wide river to a point on another bank , directly oppositeto the point from where he started . If he rows with a speed of 8 km/h , instill water and river flows at the rate of 14km//he, in which direction he should row ?
Answer» Solution : The boatman start from A and should reach B. The river FLOW is along DB, so he should row along AD. Here, `AvecD=vecv_(m)=8km//hr` Here , `AvecB` is the resultant of `AvecD and vecB`. `angle BAD=beta and angle DBA=90^(@)`n Since A and Bare directly opposite, `SIN beta=(DB)/(AD)=(v_(R))/(u_(m))=(4)/(8)=(1)/(2)` `rArr beta =30^(@)` `therefore theta=90^(@) +30^(@)=120^(@)` So, the boatman should row the boat in thedirection at an angleof `120^(@)` with river flow.