From an instrument set up at point A, the angle of elevation of point B is +16°77' while point C is +7°47'. Furthermore, it was found out that the difference in elevation between points B and C considering the effect of earth's curvature and refraction is 117.873 m. Point A is in between B and C.

What will be the level difference between points A and Bif curvature and refraction effects are also taken into account for the case as given below: Level is setup at A and staff at B. RL of A = 160 m Height of instrument at A = 1.2 m Reading of staff at B= 1.950 m Distance between A and B = 425 m

Problem 4. Point A is in between points B and C, the distances of B and C from B and C from point A are 1000m and 2000m respectively measured from point A. The angle of elevation of point B is 18°13' while that of C as Ø. The difference in the elevation of B and C is 44.4m. Considering the effects of curvature and refraction, what is the value of Ø? (Note: Assume that point C is higher) where: Earth's Curvature and Atmospheric Refraction Correction (Her): Her(m) = 0.067 K² K (km) = level distance Her K Vertical line Horizontal line Level line