Question

A company wishes to run a utility cable from point A on
the shore to an installation at
point B on the island. The island is 6 miles from the shore. It
costs $400 per mile to run the cable on land and $500 per mile
underwater. Assume that the cable starts at A and runs along
the shoreline, then angles and runs underwater to the island.
Find the point at which the line should begin to angle in order
to yield the minimum total cost. the length between A AND C is 7

Answer 1

Just noticed that both Damon and I answered a very similar question in the first of the Related Questions below
http://www.jiskha.com/display.cgi?id=1268848081

I suggest you print it out , and change the numbers, and units.