Distance of an oil well from shore - very hard

[Ian McPherson]

An oil well in an ocean is located five miles out from a straight shore line. Storage tanks are located on the shore 7 miles from the nearest point on the shore from the oil well. A pipe line is to be built from the well to the storage tanks. The cost for the underwater pipe line is twice the cost for land pipe line. At what distance from the nearest shore line point toward the storage tanks should the under water line hit the shore to minimize cost?



Ok so i drew a picture. I know that finding C of the "triangle" will give you the distance from te oil well to the point on shore. However, I can't figure out the equations, and I don't know exactly how to find the distance of 7-x.

 

[tkhunny]

What is the length of the LAND pipe?

In terms of 'x', what is the length of the WATER line? You have c^2, but this is not particularly helpful.