GeoPuzzle

[Beja]

Find D A
Observer Ob A measures pole Point B (P B) 10 meters, and then drive away from it to point (Ob A)
from point (Ob A) he sees the pole's height as 4 meters.. find distance D A.

 

[Beja]

In other words:
You know a tree's height is 10m, now you are looking at it from a distance and you see the height is 4m.
Question: how far are you (distance) from the tree?

 

[Erel]

The height cannot change. The distance doesn't matter.

You should measure the sharp angle.

Distance = <pole height> / Tan (alpha)

 

[rabbitBUSH]

OH, Heavens, @Beja Here We GO as Leonard would say : then this Leonardo would say :

OK so DA is an illusion, that changed colour and went out of focus.
Hence, is a distant object of undefined properties.

DA must therefore be 10m because when H was 10m DA was 4m ergo when H is 4 DA must be 10m.

I've been watching too much ElectionUSA stuff - - - evidently.

 

[Sandman]

Find D A

It took me quite a while, but I think I found it: