Posted by Chetan Munsell on .
The angle of elevation to the top of a building from a point on the ground is 39 degrees. From a point 50 feet closer to the building, the angle of elevation is 48 degrees. What is the height of the building?

Trig 
bobpursley,
draw the figure. You have two triangles. let x be the distance to the closer point, from the building.
Tan48=h/x
Tan39=h/(x+50)
or
x=h/tan48 and
x=h/tan39 50
set them equal, and solve for h.