surveying math
posted by Kasey .
I need help with this problem and I need to show my work. Can anyone help me?
A vertical angle of 40 is recorded between A and B. The slope distance, after meteorological corrections, is 806.388 m. What is the horizontal distance between A and B?

The theodolite measures 0° when the telescope is horizontal, and 90° when it is vertically upwards. So 40° is 40° below the horizontal.
The sloping distance is 806.388, so the horizontal distance is 806.388*cos(40°)=617.729