Sir pls reply to this I am having exam .pls.explain with all steps

V river = 5m/min     

V man = 10 m/minsuppose width of river is x mts

Case 1

if he travels due north

then his resultant velocty ( due to velocity of downstream of water) acts 30 north of east and the distane to be covered to reach the other bank increses to = x/cos 30

i.e., 2x /3^1/2 and resultant velocity is 11.2 m/min

so time taken is x / 9.7 mins

Case 2

if he travels due 30 north of east

then his resultant velocty ( due to velocity of downstream of water) actsdue north and the distane to be covered to reach the other bank will be x mts and resultant velocity is 8.7 m/min

so time taken is x / 8.7 mins

So case 1 takes least time

he should travel due north