Estimate Height of Tree

[harpazo]

I want to know if the set up is correct. This is all I need.

A man who is 2 m tall stands on horizontal ground 30 m from a tree. The angle of elevation to the top of the tree from his eyes is 28˚. Estimate the height of the tree.

Set up:

tan(28°) = (x + 2)/30

Note: x + 2 = height of tree plus height of man.

 

[Dr.Peterson]

Why are you adding? Where does that sum appear in your picture?

(Of course, they really mean to imply that the eyes are 2 meters above the ground.)

 

[harpazo]

Why are you adding? Where does that sum appear in your picture?

(Of course, they really mean to imply that the eyes are 2 meters above the ground.)

I divided the length of the tree into two parts:
From the ground to his eyes (2 meters) and from his eyes to the top of the tree (x meters). You are saying there is no need to do this. In that case, the set up should be
tan(28°) = x/30.

 

[Dr.Peterson]

I divided the length of the tree into two parts:
From the ground to his eyes (2 meters) and from his eyes to the top of the tree (x meters). You are saying there is no need to do this. In that case, the set up should be
tan(28°) = x/30.

No, I'm not. I'm saying you made a small mistake in using that split.

You divided the height of the tree, which would be x (right?) into two parts, so their sum should be x. One part is 2; what is the other? That other is a side of your triangle.

You could also do this by calling that side x; but then the height of the tree would not be x. You'd have to do an extra step after solving for x, to find the height of the tree.

 

[harpazo]

No, I'm not. I'm saying you made a small mistake in using that split.

You divided the height of the tree, which would be x (right?) into two parts, so their sum should be x. One part is 2; what is the other? That other is a side of your triangle.

You could also do this by calling that side x; but then the height of the tree would not be x. You'd have to do an extra step after solving for x, to find the height of the tree.

Stepping into lost territory. Can you please set this up for me?

 

[Dr.Peterson]

Stepping into lost territory. Can you please set this up for me?

Does your picture look anything like this? (It would be very helpful if you could take a picture of it.)



What expression represents the right side of the triangle (the ?)? It isn't x, and it isn't x+2.

 

[jonah2.0]

Beer soaked gratitude follows.

(It would be very helpful if you could take a picture of it.)

Thanks Dr. P.