is it arcsin(3/7)

let t1 be the time taken to cross the river

and t2 be the time he walks

t=t1+t2

let the direction of travel be @(i mean the angle)

t1=500/(3cos@)

(2+3sin@)t1=5t2

therefore

t2=(2+3sin@)100/3cos@

t=t1+t2=500/(3cos@)+(2+3sin@)100/3cos@

differentiating with respect to @ and equating with zero we get

(700/3)tan@+100sec@=0

therefore

sin@=-3/7

a stone is dropped from top of a tower 200m in height and at the same time.another stone is projected vertically upwards from the ground with a velocity of 50m/s.find where and where d 2 stones meet.

 

i hope u all can do.