document.write( "Question 1184727: Suppose that the orbit of a planet is in the shape of an ellipse with major axis
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Algebra.Com's Answer #815407 by ikleyn(52800) $\"\"$ $\"About$

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\n" ); document.write( "Suppose that the orbit of a planet is in the shape of an ellipse with major axis
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document.write( "To write the ellipse's equation, we should know the lengths of the two semi-axes.\r\n" );
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document.write( "For the major semi-axis \"a\", we just know it:  it is half of 500 million km, or  a = 250 millions of km.\r\n" );
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document.write( "We also know the half of the distance between the foci, which is c = 400/2 = 200 millions of kilometers.\r\n" );
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document.write( "Third thing which we know is this relation between \"a\", \"b\" and \"c\"   =  - ,\r\n" );
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document.write( "where \"b\" is the minor semi-axis.  It gives us  \r\n" );
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document.write( "     =  -  =  -  =  =  =  millions km^2.\r\n" );
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document.write( "THEREFORE, the equation of the ellipse is\r\n" );
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document.write( "     +  = 1,\r\n" );
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document.write( "where x and y are the coordinates of the planet (of the center of the planet) on the orbit, in millions of kilometers.\r\n" );
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\n" ); document.write( "\n" ); document.write( "For the ellipse canonical equation, see the first lesson from this list\r
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\n" ); document.write( "\n" ); document.write( "    - Ellipse focal property \r
\n" ); document.write( "\n" ); document.write( "    - Tangent lines and normal vectors to a circle \r
\n" ); document.write( "\n" ); document.write( "    - Tangent lines and normal vectors to an ellipse \r
\n" ); document.write( "\n" ); document.write( "    - Optical property of an ellipse \r
\n" ); document.write( "\n" ); document.write( "    - Optical property of an ellipse revisited \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
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\n" ); document.write( "\n" ); document.write( "For the properties of ellipses, read from the rest of the lessons, and find there many interesting issues,\r
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