document.write( "Question 1084921: the center of a circle is at (4,2) and its radius is 5. find the length of the chord which is bisected at (2,-1).
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Algebra.Com's Answer #699088 by ikleyn(52790)\"\" \"About 
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\n" ); document.write( "the center of a circle is at (4,2) and its radius is 5. find the length of the chord which is bisected at (2,-1).
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\n" ); document.write( "\n" ); document.write( "Below I placed much simpler solution.\r
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document.write( "1.  Make a sketch to follow my arguments.\r\n" );
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document.write( "    Let the point O = (4,2) be the center of the circle,\r\n" );
document.write( "    and let the point A = (2,-1) bisects our chord.\r\n" );
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document.write( "    Let B  and C be the endpoints of the chord.\r\n" );
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document.write( "2.  Then \"abs%28OC%29%5E2\" = \"abs%28OA%29%5E2\" + \"abs%28AC%29%5E2\",   or\r\n" );
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document.write( "    For |OC| you have  \"abs%28OC%29%5E2\" = 25  and  for  |OA| you have \r\n" );
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document.write( "     \"abs%28OA%29%5E2\" = \"%284-2%29%5E2+%2B+%282-%28-1%29%29%5E2\" = \"2%5E2+%2B+3%5E2\" = \"13\".\r\n" );
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document.write( "    Therefore,  \"abs%28AC%29%5E2\" = \"5%5E2+-+13\" = 12.\r\n" );
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document.write( "    Then |AC| = \"sqrt%2812%29\" = \"2%2Asqrt%283%29\",\r\n" );
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document.write( "         and  |BC| = \"4%2Asqrt%283%29\".\r\n" );
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\n" ); document.write( "\n" ); document.write( "Answer. The length of the chord is \"4%2Asqrt%283%29\".\r
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