document.write( "Question 968131: find an equation a circle having a diameter whose endpoints are at (2,-1) and (6,-5) \n" ); document.write( "
Algebra.Com's Answer #591674 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "We need to find the equation of the circle that has its\r\n" );
document.write( "center as the midpoint between (2,-1) and (6,-5), the green circle below:\r\n" );
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document.write( "Midpoint between (2,-1) and (6,-5), \"%28matrix%281%2C3%2C+++%282%2B6%29%2F2%2C%22%2C%22%2C%28-1%2B%28-5%29%29%2F2%29%29\"\"%22%22=%22%22\"\"%28matrix%281%2C3%2C+++8%2F2%2C%22%2C%22%2C%28-6%29%2F2%29%29\" = (4,-3) \r\n" );
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document.write( "and has its diameter as the distance between between (2,-1) and (6,-5)\r\n" );
document.write( "and its radius as half that:\r\n" );
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document.write( "Therefore its center is (4,-3) and its\r\n" );
document.write( "radius is one-half the diameter \"2sqrt%282%29\".\r\n" );
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document.write( "Its equation is\r\n" );
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document.write( "\"%28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2\"\r\n" );
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document.write( "\"%28x-4%29%5E2%2B%28y-%28-3%29%29%5E2=%282sqrt%282%29%29%5E2\"\r\n" );
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document.write( "\"%28x-4%29%5E2%2B%28y%2B3%29%5E2=4%2A2\"\r\n" );
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document.write( "\"%28x-4%29%5E2%2B%28y%2B3%29%5E2=8\"\r\n" );
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document.write( "Or you can multiply it out and rearrange to get this:\r\n" );
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document.write( "\"x%5E2%2By%5E2-8x%2B6y%2B17+=+0\"\r\n" );
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document.write( "Edwin
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