A man swims with a constant absolute velocity irrespective of the current in water. He can swim from a point P on one bank of river to a point Q just opposite the other in time t when the water is still. He takes time `t_(1)` to swim across along the same straight path PQ when the river flows down with a uniform velocity . The river velocity is `(b)/(t t_(1)) sqrt"" (t_(1)^(2) - t^(2))`
where b is the breadth PQ of the river.

Answer

1