60m A site layout of a road construction site is shown in the following drawing 200m point C point X point B point A Point B lies 200m downstream of point C on the opposite bank of point A of a 60m wide ravine which has a river at the bottom. Between these two points lies a point at X where the construction costs are minimised. An access road is to be constructed from A to B and it requires building a bridge over the ravine. The cost of construction in units of 100,000 per line metre are: 5 units per m for bridge construction, and 3 units per m for road construction Derive a formula to calculate the cost of constructing the access road and bridge, then use the formula to calculate the construction cost when: a) The bridge makes the shortest possible crossing the ravine. b) The bridge spans directly from A to B. 5% 5% c) Use your formula to determine the position of point X and demonstrate that the construction costs have been minimised. Solve this question using the graphical method. 5% d) Use your formula to determine the position of point X and demonstrate that the construction costs have been minimised. Solve this question using the calculus derivative method. 5%