Find the angle of elevation of T FROM P

richiesmasher

Junior Member
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Dec 15, 2017
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111
Hello I have a question here.
I will post two pictures including a diagram interpreting what I drew for the question.

From my diagram I have obtained the distance PR to be approx 118.7m using the Sine Law, in this particular case, I did

PR/Sin95° = 75/sin39°, from here I just solved to get the 118.7m.

Now they ask for the angle of elevation of T from P... According to my interpretation of the diagram, it looks like a vertical line.

I would think its zero, but it is 13.1°.

I'm stuck at this point. The only thing I can think of is that I drew the diagram wrong, But I think I followed it quite well.

 
Angle of Elevation is ALWAYS measured by comparison to the HORIZONTAL. If P is directly below T, the Angle of Elevation from T to P is -90º. However, negative values are unusual. Typically, one would prefer Angle of Depression for measurement below the horizon.
 
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You could have added some perspective to your diagram; then TQP would reflect reality, instead of lying on a straight line. That is: P, Q, and R are all on the ground, and QT is a vertical tower rising out of the ground.

But, you're okay. Simply draw another diagram, for the second part of the exercise.

PQT is a right triangle, where PQ is the horizontal leg (i.e., the ground) and QT is the vertical leg (i.e., the tower).

You know angle PQT.

You know length QT.

You can find length PQ, using the Law of Sines again.

You can then find angle TPQ, which is the angle of elevation from P to T (i.e., from the ground to the top of the tower). :cool:
 
I'd like to agree thoroughly with mmm4444bot.

Very often, a drawing doesn't have to be particularly perfect. A rough idea can be just fine. However, every once in a while, a "rough idea" will be quite misleading. This REQUIRES that you try the drawing over again - with substantial care!
 
Thank you for the replies TKhunny and mmmbot, I was thinking that same thing at the start, it should have real life perspective, but I second guessed myself.
I understand exactly how TPQ forms a right triangle, so I did solve in the end.
 
Denis has an itch, to spend some time playing Xs & Os you know where. (It's been awhile.)
 
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