document.write( "Question 1186658: An ellipse has vertices (2 − √ 61, 5) and (2 + √ 61, 5), and its minor axis is 12 units long. Find its standard equation and its foci.
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Algebra.Com's Answer #817622 by ikleyn(52802)\"\" \"About 
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\n" ); document.write( "An ellipse has vertices (2 − √ 61, 5) and (2 + √ 61, 5), and its minor axis is 12 units long.
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\n" ); document.write( "\n" ); document.write( "            It can be done (and it should be done) in much shorter way,  than @MathLover1 does it.\r
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document.write( "Looking at the foci coordinates, you see that they are on the horizontal line y = 5.\r\n" );
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document.write( "So, the major axis is horizontal, parallel to x-axis, and the length of the horizontal axis is  \r\n" );
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document.write( "     \"2%2Bsqrt%2861%29\" - \"%282-sqrt%2861%29%29\" = \"2%2Asqrt%2861%29\".\r\n" );
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document.write( "Hence, the length of the major semi-axis  \"a\"  is half of it, i.e.  a = \"sqrt%2861%29\".\r\n" );
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document.write( "The length of the minor semi-axis is  b = \"12%2F2\" = 6.\r\n" );
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document.write( "The center of the ellipse is the point (2,5).\r\n" );
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document.write( "THEREFORE, the standard form equation of the ellipse is\r\n" );
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document.write( "    \"%28x-2%29%5E2%2F61\" + \"%28y-5%29%5E2%2F6%5E2\" = 1.    ANSWER\r\n" );
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document.write( "The distance from the center to the focus is  c = \"sqrt%28a%5E2+-+b%5E2%29\" = \"sqrt%2861-36%29\" = \"sqrt%2825%29\" = 5.\r\n" );
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document.write( "The foci are  (2+5,5) = (7,5)  and  (2-5,5) = (-3,5).\r\n" );
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