posted by wenjelin on .
A man standing 9 meters above the ground observes the angles of elevation and depression of the top and bottom,of the top of the monument in luneta 6 degrees and 50 minutes and 7 degrees and 30 minutes respectively.Find the height of the monument?
did you make a diagram ?
let the top of the monument be A and the bottom be B
let the person's position be at P
Draw a horizontal from P to AB to meet AB at C.
then CB = 9
angle APC = 6°' 50' or 6.8333°
angle BPC = 7° 30' or 7.5°
Using triangle PBC you can find PC using tan7.5°
Once you have PC you can go into the other triangle and again using the tangent ratio find AC
Height of monument = AC + 9