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Unformatted text preview: Douglass Houghton Workshop, Section 1, Mon 11/21/11 Worksheet Nigh on Thanksgiving 1. Weve been working on the problem of finding the shortest road network between three cities in the plane. In the case we considered, the three cities were at the corners of a 45 -45 -90 triangle with legs 10 miles long. The simplest idea is to just build roads along the legs; that makes a network of length 20. But by constructing a Y-shaped network like the one at the right, we found b b b b A B C 10 10 x The length of the network is x + 2 radicalBig 100- 20 x cos(45) + x 2 . We can improve from the simple 2-road solution ( x = 0, length = 20) by increasing x . For instance, when x = 5, the network has length 19.74. (a) Consider the case where the triangle is still isosceles and the legs still have length 10, but the angle at B is 70 . Write a formula for the length of the network. (b) Can you find a value of x which beats the 2-road solution ( x = 0, length = 20)? b b b b A B C x (c) Now suppose the vertex angle is very obtusesay 150 . Find a formula for the length of the network.....
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This note was uploaded on 01/28/2012 for the course MATH 146 taught by Professor Conger during the Winter '08 term at University of Michigan.
- Winter '08