Homework Help: precal

Posted by shep on Sunday, July 15, 2012 at 9:47pm.

From a point B that is 9 meters above level ground , the angle of elevation of the top of a building is 43 degrees and the angle of depression of the base of the building is 7 degrees. What is the height of the building.

(tell what formula and why you used it will very much be appreciated)

precal - Steve, Monday, July 16, 2012 at 10:09am
draw a horizontal line from B to where it intersects the building wall. Call that point C.

Label the top of the building A, and the bottom D.

The height of the building is thus

AD = AC + CD

AC/BC = tan 43°
CD/BC = tan 7°

Now, you see that without knowing the distance BC, there is no way to determine the height of the building. The farther away you are, the higher the building.

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