Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In trigonometry to measure the height or distance of objects we consider the distance between the observer and object to be straight. But the surface of the earth is curved. Assuming the line to be straight, doesn't it cause any error, or are the distances too small to cause significant error?

share|cite|improve this question
It depends on what you mean by significant error, but isn't this more of a physics question than a mathematics question? – mrf Jan 29 '13 at 12:43
"Locally" the Earth, or at least the surface of the ocean, is flat. For modest distances, it makes no practical difference. What sorts of distances do you have in mind? $100$ metres? $1$ km? $10$ km? $100$? – André Nicolas Jan 29 '13 at 12:45
You are more likely to have error caused by localized variation in topology unless you are on the ocean. There will always, however, be some error because of this assumption. This is a useful example for classes but I generally use trig for more complex systems then finding the height of a building or other tall object. – kaine Jan 29 '13 at 13:07
For finding inaccessible objects like mountains we use trigonometry. Doesn't it result in errenous answer? How is it rectified? – Ranjan Yajurvedi Jan 29 '13 at 13:19
@RanjanYajurvedi: I can't answer but suggest that you may look up in textbooks on surveying and cartography. – Mok-Kong Shen Jan 29 '13 at 15:40

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.