calculating height by fixed angle of inclination

[goofball]

so i am trying to find some clarification of use for this method and not getting any. what i want to know is how far from the eye should i position my 45 deg. triangle and where upon the eye should i position its bottom, meaning should the bottom of my triangle be "flush" to my sight as i look along the slope to the apex (which i assume is best for the most accurate measure) ? how much do these influence my calculation ? dos the math change if the triangle is 1" away from my eye as opposed to 2" or 3" or 4" ? and what margin of error should i factor in regardless ?

[uintahiker]

Why bother?!

I think it doesn't matter, as long as you are consistent throughout.

Find something that you know what the height is and try it out & change a few of the variables you've called out. You'll likely find that the difference is negligible.

[uintahiker]

Also- try referring to it by a different name & you might come up with more applicable results, ie "fixed angle of elevation."
Hope this helps.

[Sombeech]

If the slope is 45

[goofball]

looks like i made it more complicated than needed.

that is exactly what i am wanting to do sombeech, want to be able to calculate, say, the distance from a drop off above to teh canyon floor below by sighting along the slope of my right triangle and then walking out the distance b to find a, when my drop above just hits the apex of B by sightin along c. just wasn't sure if my sighting method would matter much, i am not a math type at all. wheres a muslim when you need one ? didn't they decipher trigonometry or whatever it is i am mucking up all to hell here ?

i'll take uinta's advice and just do test runs.

[Iceaxe]

What exactly are you trying to do? You can solve a triangle provided you know any three things about it except angle-angle-angle.

If you are looking for an elevation with a 45 degree triangle you already know all the angles so you need at least one length.

[Sombeech]

I see.... so you want to look down a triangle such as a framer's square to a point on the ground below you, to measure how far up it would be?

Yeah so if you're at a cliff edge, stand right near the edge, look down the 45

[goofball]

I see.... so you want to look down a triangle such as a framer's square to a point on the ground below you, to measure how far up it would be?

almost. i'll be standing below though, trying to calculate the height UP to the drop. the rest of your advice is much appreciated and exactly what i was wondering about.

so this diagram shows what i am getting at.

[ATTACH]49395[/ATTACH

adjusting my position i'll sight along teh slope of the right triangle until the bottom of the cliff above is visible just at the traingles apex, then walk out the distance from that spot to teh cliff face to get the height. trying not to wa]ke the slumbering beast entombed w/in the rock of course.

[Sombeech]

I see. Your main concern will still be keeping the triangle level though so you can get as close as possible to the exact 45

[Mtnseeker1]

Range finder maybe? Transit? Gunners Quadrant? Sounds like basically intersect and resect but only in a vertical manor.
You will need several things
1- level
2-distance of level
3- a tool that prescribes elivation that is ajustable as not everything is going to be 45*
4- much better math than mine LOL

[Last Child]

As someone who measures land for a living I can tell you that if you are serious about this then you should bag the 45 degree triangle thought. Unless you really really know what you are doing this will be next to impossible to give you an accurate measurement. The best method to do this is to use a clinometer or inclinometer. You need to take into account your height, the angle from your eye to the base of the target, the angle from your eye to the top and the distance from you to target and the assumption that the cliff is vertical. Do a search on how to use a clinometer and you will come up with stuff on how to measure tree heights. This is what you want to learn how to do. The complexity of it will be determined on whether or not you can use right triangle math. I would guess not because your eye height will more than likely be below the base of the cliff. It's not hard if you are semi math competent and do it right. Also do a search for how to make a homemade clinometer. If you want accurate readings I'd suggest buying one though. A simpler and more accurate method would be to buy a 100, 200, or 300 foot cloth measuring tape. Just weigh down the end and lower it over the edge and wind it back up when done. You would be surprised at how much error can be produced by what seems to be a small error in readings or measurments or a math error. Better yet get both and practice your hand at the clinometer using the tape to check your math. Also I think they make electronic clinometers that will do the math for you. Probably $250 or so though.

[greyhair biker]

try this method
http://www.jimloy.com/geometry/tree0.htm

[Mtnseeker1]

Yes sir like I said entersect and rescect in a vertical manor.