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May 20th, 2010, 09:39 PM  #1 
Newbie Joined: May 2010 Posts: 4 Thanks: 0  Ellipse radius at specific angle?
Okay, I found some formulas but I did not find any that I would believe, but: Earth minor radius is at pole and it is 6356.7519km and major radius is 6378.1366km at equator and now I want to know what is radius at my latitude of 60° at Helsinki Finland, how do I calculate this? And please, in simplest way you can say it Thank you. 
May 21st, 2010, 04:27 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 20,927 Thanks: 2205 
If the earth's crosssection is an ellipse, its equation is (x/6378.1366km)² + (y/6356.7519km)² = 1. For your latitude, y = (?3)x and the radius there is 2x, so substitute for y, find x² and then find 2x. 
May 22nd, 2010, 04:10 AM  #3 
Newbie Joined: May 2010 Posts: 4 Thanks: 0  Re: Ellipse radius at specific angle?
Thank you, but I'm not sure did I understand, I could think my ass off or can you say it in more simplier way and even better I would be very thankful if you would show how its calculated all the way to the answer, but you don't have to if you don't want to or have the time for helping notsomathgenious like me 
May 23rd, 2010, 09:44 PM  #4 
Global Moderator Joined: Dec 2006 Posts: 20,927 Thanks: 2205 
What exactly puzzles you? Do you understand that tan(60°) = ?3? What did I give that isn't simple?

May 25th, 2010, 07:26 AM  #5 
Newbie Joined: May 2010 Posts: 4 Thanks: 0  Re: Ellipse radius at specific angle?
I don't understand what do I have to do with: 1,7320508075688772935274463415059 = tan(60°) = ?3, to get radius? 
May 25th, 2010, 11:40 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 20,927 Thanks: 2205 
You use the equation I gave and make the substitution I suggested!What exactly is stopping you from doing that?

May 27th, 2010, 03:31 AM  #7 
Newbie Joined: May 2010 Posts: 4 Thanks: 0  Re: Ellipse radius at specific angle?
So, what is stopping you for showing me how would you calculate it and what is the answer, you should clearly see that I'm not understanding any that you are saying.

May 27th, 2010, 05:34 PM  #8 
Global Moderator Joined: Dec 2006 Posts: 20,927 Thanks: 2205 
You originally asked to be told (in simple terms) how to calculate the radius, so I told you what to do. You didn't originally ask for the value that results from doing that calculation. Without knowing what you are capable of understanding, I don't know how much detail to give. If you don't understand even a standard equation for an ellipse and you don't understand basic algebraic concepts, where should I start? I can't even refer you to any textbook, as you presumably wouldn't understand that either. 
May 15th, 2012, 12:08 PM  #9 
Newbie Joined: May 2012 Posts: 1 Thanks: 0  Re: Ellipse radius at specific angle?
I am trying to find the same formula and an example of it worked out with values. I am good at learning math once I see something worked out. While I work with trig and algebra functions daily, I am not a mathmatician and it has been twenty years since I last took a math class. If a noncondescending person who actually has the ability to work this problem out would do so showing the formula with the values plugged into the formula I would appreciate it.


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