# Measurement

• Jun 3rd 2008, 04:20 PM
brownb01
Measurement
ok everyone i have a big problem i dont get this question could somebody smart ( most likely everyone here), help me on it it would be nice if they can make a diagram for it in paint and show me it so i know how to make the diagrams aswell thanks! email is brownb01_@hotmail.com

or u can just post it here what ever is easier for you, ok the question

Height of a building from the window of one building, Sam finds the angle of elevation of the top of a second building is 41(degrees) and the angle of depression of the bottom is 54(degrees) the buildings are 56m apart. find, to the nearest metre,

a) the height of the second building

also can some one tell me the rules of the degrees like the corresponding like if the make a Z then the degrees are the same can someone tell me them all thanks.. !
• Jun 3rd 2008, 05:59 PM
Jonboy
could you re-write the problem more clear? that's one long sentence right here:

"Height of a building from the window of one building, Sam finds the angle of elevation of the top of a second building is 41(degrees) and the angle of depression of the bottom is 54(degrees) the buildings are 56m apart."
• Jun 3rd 2008, 06:00 PM
brownb01
from the window of one building, Sam finds the angle of elevation of the top of a second building is 41(degrees) and the angle of depression of the bottom is 54(degrees) the buildings are 56m apart. find, to the nearest metre,

a) the height of the second building

directly from the textbook hope its understandable now
• Jun 3rd 2008, 06:42 PM
Jonboy
i think i might understand it now.

here's a picture for ya:

http://img393.imageshack.us/img393/9782/brownb01ok7.jpg

So $\displaystyle AD = 56$

Use your Right Triangle Trig Functions to get the length of BD, then DC, add them together and you have the length of the second building.

For checking purposes, I'll show you what you should get.

If we start at $\displaystyle \angle DAB$, we know the adjacent side.

We need the opposite side. So use $\displaystyle Tan$

$\displaystyle Tan\,54 = \frac{BD}{56}$

Criss-Cross Multiply: $\displaystyle BD = (Tan\,54)(56)$

Then go to $\displaystyle \angle DAC$

Once again, use $\displaystyle Tan$

$\displaystyle Tan\,41 = \frac{CD}{56}$

$\displaystyle CD = (Tan\,41)(56)$

So: $\displaystyle BC = (Tan\,54)(56) + (Tan\,41)(56)$

Now round it to the nearest meter.
• Jun 3rd 2008, 07:01 PM
brownb01
wow thanks so much, the answer is correct, but i cannot see the picture can you some how email it as an attachment? pleaseee i triedd using the link but it says 504 gateway timeout. also i was wondering can you explain depression and elevation to me (the rules for it)
• Jun 3rd 2008, 07:10 PM
Jonboy
i'll attach the picture on this post.

the angle of depression and elevation are both the angle between the horizontal line and the line of sight.

the line of sight has a positive slope for the angle of elevation, while the line of sight has a negative slope for the angle of depression.

the horizontal line can be thought of as the line that is made as if the person is looking straight ahead.
• Jun 3rd 2008, 07:28 PM
brownb01
wow LOL my diagram was so close to yours, i jus had the degrees at Angle B and C instead of the top thanks alot man have a good day.