a river with a right-angle bend, longest boat of length c wanted
Source: Vietnam MO 1978 P5
July 29, 2018
problemgeometrymaximumright angle
Problem Statement
A river has a right-angle bend. Except at the bend, its banks are parallel lines of distance apart. At the bend the river forms a square with the river flowing in across one side and out across an adjacent side. What is the longest boat of length and negligible width which can pass through the bend?