Radius of Earth at specific angle,

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Discussion Overview

The discussion revolves around calculating the radius of the Earth at various latitudes, specifically from 0° to 90°. Participants explore the mathematical formula provided in a Wikipedia article and seek clarification on its application, particularly for specific angles like 61° and 34°.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant requests assistance in understanding how to calculate the Earth's radius at different latitudes using a specific formula, expressing a lack of mathematical background.
  • Another participant provides the formula for calculating the radius at a given latitude, including specific values for the semi-major and semi-minor axes of the Earth.
  • A participant expresses difficulty in completing the calculation, indicating they have followed the initial steps but are unsure how to proceed further.
  • A later reply indicates that the participant successfully completed the calculation after receiving help, expressing gratitude for the assistance.

Areas of Agreement / Disagreement

Participants generally agree on the formula to use for the calculation, but there is uncertainty regarding the execution of the calculations and the interpretation of results. The discussion remains unresolved in terms of a complete step-by-step solution.

Contextual Notes

Limitations include the participant's self-identified lack of mathematical education, which may affect their understanding of the formula and calculations. There are also unresolved mathematical steps in the calculation process.

TheJere
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I was going to post this on Earth-forum here but I thought that you guys here can help me better with this. I'm trying to get the radius of Earth on every latitude degree from 0° to 90°, knowing 0° at Equator is ~6378,137km and 90° at North/South Pole is ~6356,7523km (source Wikipedia). In Wikipedia there is formulas to calculate radius at any angle, but I don't have a clue how to calculate with it. Now to what I'm asking here:
Can someone please explain to me (one that doesn't have even College education on mathematics) so that I could understand it? Best way to explain would be adding some examples like for 61° and 34°?

Now, I have been struggling with this for a very very long time, and I am already being really thankful for the one that explains this to me.

Wikipedia article:
http://en.wikipedia.org/wiki/Earth_radius#Radius_at_a_given_geodetic_latitude
 
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No college math needed here, just how to use a calculator! The applicable formula is the first:
"The distance from the Earth's center to a point on the spheroid surface at geodetic latitude"
R= \sqrt{\frac{(a^2cos(\phi))^2+ (b^2sin(\phi))^2}{(acos(\phi))^2+ (bsin(\phi))^2}}
And you are given that a= 6,378.1370, b= 6,356.7523.

So if, for example, \phi= 61^o, cos(\phi)= cos(61)= 0.4848096 and sin(\phi)= sin(61)= 0.8746197.

So a^2cos(\phi)= 19722361, b^2sin(\phi)= 35341895, acos(\phi)= 3092.182, and bsin(\phi)= 5559.741 where I have rounded to 7 significant figures. Can you finish?
 
I'm afraid and really sorry, but I think I can't finish, haha. I put numbers you had calculated on formula and I keep having number 435114,36..., double-checked. Thank you very much for the your explain this far, I get it to the point you have calculated it, but I'm afraid I have to ask you to tell me how to finish it?
 
Oh, now I got it right, THANK YOU very very much, I'll be thankful for you for really long time!
 

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