The Height of the Tower

An observer is on the bank of a river at A, opposite a tower TF.  His task is simply to find the height of the tower.  He can not get to the tower because of the river and so he has to do this from where he is.  He is equipped only with an inclinometer, a marking pole and a measuring tape. 

A    His first thought is to try to estimate the distance AF directly.  Can you advise him how to do this by going to different points on his side of the river?     (hint: similar triangles...)

B    He then measures the angle of elevation of T from A, and finds that it is 30o.  How can he then find the height of the tower?  

C    He has another idea, and walks back to B, 35 m behind him;  the angles of elevation from A and B are then 30o and 20 o.  What does this make the height of the tower?

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Last modified: June 18, 2007