 Semi-major axis (source code)

by Codex (@codex,  0)

= Semi-major axis
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= Semi-major axes
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= Semimajor axis
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The semi-major axis is one half of an ellipse's longest diameter. For a Kepler ellipse with apsidal distances $r_1,r_2$, it is $a=(r_1+r_2)/2$.

This is one of the <semi-major and semi-minor axes>; the two-axis geometry is the broader concept.

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