Originally Posted by

**chrozer** So would the equation be $\displaystyle \dfrac{x^2}{\bold{\color{red}4150}^2}+\dfrac{y^2}{ 4196.7^2}=1$?

I'm still kinda confused on the drawing:

[*]How did you figure the distance of the blue line?

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[*]If the diameter of the earth is 8000, then the radius should be 4000, why is there a 4100?.......That's the distance from the center of the Earth to the satellite at it's minimum height.

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[*]And what is with the 50, 8300, and 4150?.......The diameter of Earth + maximum height + minimum height ist the complete major axis of the ellipse. 8000+200+100 = 2a.

**a = 4150**

Since the center of the Earth is a focus the excentricity of the ellipse is 4150 - 4100 = 50

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As you may know the ellipse has the property: $\displaystyle \bold{b^2 + e^2 = a^2}$

I have drawn the minor semi-axis in blue. The slanted line has the length a.