SOLUTION: the angle of depression from the top of a tall building to the top of a shorter building is 15. the angle od depression to the base of the shorter building is 38. if the shorter bu

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Question 184019: the angle of depression from the top of a tall building to the top of a shorter building is 15. the angle od depression to the base of the shorter building is 38. if the shorter building is 170feet tall, what is the distance between the two buildings.
Answer by Edwin McCravy(20062) About Me  (Show Source):
You can put this solution on YOUR website!
the angle of depression from the top of a tall building to the top of a shorter building is 15. the angle od depression to the base of the shorter building is 38. if the shorter building is 170feet tall, what is the distance between the two buildings.



First let's draw in this right triangle to
indicate the angle of depression to the top
of the shorter building from the top of the
tall building:



The distance between the buildings is X, and that's
what we want to find.

From that right triangle we get

matrix%281%2C3%2C+++++++%22tan%2815%B0%29%22%2C+%22=%22%2C+Y%2FX++%29

Multiply both sides by X

matrix%281%2C3%2C%22Xtan%2815%B0%29%22%2C+%22=%22%2C+Y++%29

or

matrix%281%2C3%2CY%2C+%22=%22%2C+%22Xtan%2815%B0%29%22%29

Next redraw the figure, but this time let's 
draw in this right triangle to indicate the 
angle of depression to the bottom of the 
shorter building from the top of the taller
building:



From that right triangle we get

matrix%281%2C3%2C+++++++%22tan%2838%B0%29%22%2C+%22=%22%2C+%28Y%2B170%29%2FX++%29

Multiply both sides by X

matrix%281%2C3%2C%22Xtan%2838%B0%29%22%2C+%22=%22%2C+Y%2B170++%29

or

matrix%281%2C3%2CY%2C+%22=%22%2C+%22Xtan%2838%B0%29-170%22%29

Now we put those two equations together:



We set the right sides equal, since they both 
equal to Y:

matrix%281%2C3%2C%22Xtan%2838%B0%29-170%22%2C+%22=%22%2C+%22Xtan%2815%B0%29%22%29

or

matrix%281%2C3%2C%22Xtan%2838%B0%29-Xtan%2815%B0%29%22%2C+%22=%22%2C+170%29

Factor out X on the left

matrix%281%2C3%2C%22X%5Btan%2838%B0%29-tan%2815%B0%29%5D%22%2C+%22=%22%2C+170%29

Get your calculator and find this value: 

matrix%281%2C1%2C%22tan%2838%B0%29-tan%2815%B0%29%22%29

which is .5133364341, so we substitute this 
in the bracket:

matrix%281%2C3%2C%22X%5B.5133364341%5D%22%2C+%22=%22%2C+170%29

Divide both sides by .5133364341%29

matrix%281%2C3%2CX%2C+%22=%22%2C+170%2F.5133364341%29

matrix%281%2C3%2CX%2C+%22=%22%2C+170%2F.5133364341%29

matrix%281%2C3%2CX%2C+%22=%22%2C+331.1668308ft%29

or about 330ft to the nearest ten feet.

Edwin