A little problem

a small query for all you mathematicacal geniusses out there.

BunnyHare...

Not a mathematical genius but here is how we estimate the height of a
object in Guides. If I have remembered it correctly :-))

Select your object, building, tree etc.
Obtain a stick approximately 2 metres high
Pace away from the object to be measured somewhere round about 7 or 8
metres and plant the stick. (assuming the object is higher than 7 or 8
metres)
Walk backwards from the stick you just planted and lay flat on the
ground to check. When you reach a point where the top of the stick is
level with the top of the tree (or object being measured)
The height of the tree is then
Height of stick x distance from your head (eyes) to the base of the
stick plus the distance from base of stick to base of the tree (object
being measured) divided by distance from base of stick to your head
(eyes)

So eg. You walk 8 metres from tree, plant stick 2 metres high, then
walk another 3 metres to lie down and match top of stick with top of
tree then calculation would be
2x (8+3)/3 = 7.3m

As it is now fully 50 years since I left behind the world of sines, cosines,
logs and anti-logs etc, I have a problem that I do not know how to solve. I
might have when I was a kid, and when I did my Scout Badge, but not now.

The simple thing is:- I have a structure, the height of which I need to
estimate. Simple thing, but a tape is out of the question, nor can I climb
the thing to drop a piece of string. The world will not stop if I cannot get
the answer, but the knowledge will add a little spice to a story wot I am in
the middle of scribbling.

Any offers?

david...

well, if you like sines, a sample solution is at

a very low-tech solution i learned years ago for approximating the height
of items not too tall is to have a person of known height stand by the
item and then a second person stand back 20-30 feet and approximate how
many times taller the item is than the person. it's pretty reliable up to
20-30 feet... :) and requires no numbers.... :)