A house (H) is located on an island that is 200 north of a point (A) on the shore. A Power station (p) is located on the shoreline at a point 400 m west of Point A. An electric cable is going to be laid from the power station to the house. It costs $12/m to lay underwater and $6/m to lay underground. How should the cable be placed so that the cost is a minimum and what is this minimum cost?
Please help, exam is in 1.5 hour. Thanks