Question 249561
here's your diagram.


<a href = "http://theo.x10hosting.com/problems/249561.html" target = "_blank">http://theo.x10hosting.com/problems/249561.html</a>


you draw a line parallel to the ground from the window to the opposite building.


that would be line AB


you draw a line from the windoiw to the base of the building next door.


that would be line AC.


you draw a line from the window to the top of the building next door.


that would be line AE.


your angle of depression is angle BAC.


your angle of elevation is angle EAB.


line AD is 30 feet.


so is line BC because it's on the opposite end of the rectangle that  you drew which is rectangle ABCD.


you need to find the length of line AB.


use tan(31) = BC/AB go get line AB.


use tan(40) = EB/AB to get line EB.


height of building is line EC which is the sum of lines EB and BC.


any further questions, send me an email.


i'll be checking in the morning.