Posted by jeremey on .
From h a point A that is 10 meters abov level ground, the angle of elevation of the top a building is 42 degrees and the angle of depression of the base of the building is 8 degrees approximate the height of the building

Pre calculus 
drwls,
Let the building height be Y
Let the horizontal distance to the building be h.
h tan 42 = a
h tan 8 = b
Y = a + b = h (tan42,+ tan 8)
For the value of h, use
h tan 8 = 10 m