An oil company wishes to run a pipe from point a on the shore to point b on the island (see figure). the island is 5 miles from shore. it costs $1,000 per mile to run cable on land and $2,000 per mile underwater. assume that the cable starts at point a and runs along the shoreline, then angles at point d and runs underwater to the island. let the distance between a and c be 8 miles, and the distance between c and d be represented by x express the cost of laying the pipe as a function of x.