Two boats `A` and `B` moved away from a buoy anchored in the middle of a river along the mutually perpendicular straight lines. `A` moved along the river and `B` at fight angle to it Having moves off equal destances from the boy, the boats returned. Find the ratio of the times of motion of the boats, if the velocity of each boat with rspect to still warer in `eta` times greater than the velocity of warer current.

Explanation

`t_(A)=(s)/(nu+u)+(s)/(nu-u) =(2s nu)/((n^(2)-1)u^(2)) =(2ns)/((n^(2)-1)u)`
`t_(B)=(2s)/(sqrt((nu)^(2)-u^(2)))=(2s)/(u sqrt (n^(2)-1))`
`(t_(A))/(t_(B)) =(n)/(sqrt(n^(2)-1))`.