Four hills A, B, C and D are in straight line. The elevations are A = 247 m, B = 236 m, C = 314 m and D = 396 m respectively. The distances of B, C and D from A are 12 km, 45 km and 60 km respectively. Considering the effect of curvature and refraction of the earth. a. Compute the height of equal towers on A and D to sight over B and C with a 3 m clearance. b. Compute the elevation of the line of sight at B with the installation of equal heights of tower at A and D. c. Compute the height of tower at A with a clearance of 3 m at C so that D will be visible from A, if the height of tower at D is 2 m.

Four hills A, B, C and D are in straight line. The elevations are A = 247 m, B = 236 m, C = 314 m and D = 396 m respectively. The distances of B, C and D from A are 12 km, 45 km and 60 km respectively. Considering the effect of curvature and refraction of the earth. a. Compute the height of equal towers on A and D to sight over B and C with a 3 m clearance. b. Compute the elevation of the line of sight at B with the installation of equal heights of tower at A and D. c. Compute the height of tower at A with a clearance of 3 m at C so that D will be visible from A, if the height of tower at D is 2 m.