
Eric S.
asked 11/07/22From a point A that is 8.30 meters above level ground, the angle of elevation of the top of a building is 37°50'
and the angle of depression of the base of the building is 15°30'. Approximate the height of the building. (Round your answer to the nearest tenth.)
1 Expert Answer

Simon C. answered 11/07/22
Undergraduate Tutor, Friendly, Good at Simplifying Complex Concepts
In this video I show how we can use the property of the tangent function, where tangent(angle) = opposite/adjacent, to determine the total height of the building.
Written calculations (in case video doesn't process, I hope you can see my diagram):
[EDIT: I forgot to convert the angle measurements to degrees, so the correct angle of elevation should be approximately 37.83 degrees and the angle of depression should be 15.5 degrees. My apologies for the confusion]
Angle of Elevation: 37°50' = 37 + 50/60 ° = 37.83°
Angle of Depression: 15°30' = 15 + 30/60 ° = 15.5°
tan(15.5°) = 8.3 / BC
BC = 8.3 / tan(15.5°)
BC = 29.9
tan(37.83°) = CD / BC
CD = BC x tan(37.83°)
CD = 29.9 x tan(37.83°)
CD = 23.2
Height = 8.30 + CD = 8.30 + 23.2 = 31.5 (rounded to nearest tenth)
Again, my apologies for the confusion in the video.

Doug C.
Hmm, I got slightly different answer (wonder if it could be the conversion of minutes to degrees? desmos.com/calculator/bdlwsslr1l11/07/22

Simon C.
Ah I forgot yes! My apologies, I don't deal with minutes too often. Once the angles are converted to the right units, the rest of the problem should be correct.11/07/22

Simon C.
The written answer should now be correct, thank you for pointing out the error. I hope the showing of the process in the video is helpful, but the correct calculations are below it.11/07/22
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Mark M.
Did you draw and label a diagram?11/07/22