I can't understand

Question

A phone line runs east along a field of 2 miles and then north along the edge of the same field for 2.75 miles. If the phone line cost 3500 per mile to install, how much could have been saved if the phone line had been installed diagonally across the field?

Answer 1

Use Pythagorean Theorem to determine diagonal length = sqrt(2^2 + 2.75^2) = 3.4 miles

cost = 3.4 miles * $3500/mile = $11,900

currently cost is: 2 + 2.75 = 4.75 miles * $3500/mile = $16,625

savings = $16,625 - 11,900 = $4,725.