This is a tough one...

Oil must be piped from a proposed oil derrick site located in the gulf of Mexico 3 miles offshore from Bikoxi, MA, to a refinery in Gulfport, MS, which is 13 miles to the west of Biloxi. If it costs 2.5 times as much to lay pipe underwater as it does to lay pipe underground, then to what point should the pipe get to shore in order to minimize the cost of laying pipe??

What i'am thinking.... Seems to be a triangle where you need to find the hypotenuse

See attachment for pic