(3) A power line is to be constructed from a power station at point A to an island at point C, which is directly 1 km out in the water from a point B on the shore. Point B is 4 km downshore from the power station at A, It costs $5000 per km to lay the power line under water and $3000 per km to lay the line under ground. The line comes to shore at point S downshore from A. (Note that S could very well be A or B.) Let x = the distance from B to S. Express the cost of laying the line as a function of x
SOLUTION:
z2 = x2 + 12 = x2 + 1 z =
Cost = 3000(4 - x) + 5000z = 3000(4 - x) + 5000