The top of a tower signal at B 2000m away from A was sighted through a transit with recorded vertical angle of 30 30'. The height of the mast is 12m and the HI of the transit above the point where it...

Extracted text: The top of a tower signal at B 2000m away from A was sighted through a transit with recorded vertical angle of 30 30'. The height of the mast is 12m and the HI of the transit above the point where it is set is 1.10m. The elevation of the point under the transit A is 133.3m. Compute the elevation of the base of the signal B.