Radius of Earth at specific angle,

AI Thread Summary
The discussion focuses on calculating the Earth's radius at various latitudes, specifically from 0° at the Equator to 90° at the poles. The user seeks a simple explanation of the formula provided in a Wikipedia article, which requires basic trigonometric functions and the values for the semi-major and semi-minor axes of the Earth. An example calculation for 61° latitude is shared, demonstrating the use of cosine and sine functions to derive necessary values. The user expresses gratitude for the assistance in understanding and completing the calculation. The conversation highlights the importance of clear explanations for complex mathematical concepts.
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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