document.write( "Question 551180: How do i Write the equation of a circle with endpoints of the diameter at
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Algebra.Com's Answer #359504 by jim_thompson5910(35256)\"\" \"About 
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Recall that the general equation of a circle is \"%28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2\".\r
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\n" ); document.write( "\n" ); document.write( "So we need the center (h,k) and the radius squared \"r%5E2\".\r
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\n" ); document.write( "\n" ); document.write( "First, let's find the center (h,k).\r
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\n" ); document.write( "\n" ); document.write( "Since the center is the midpoint of the line segment with endpoints (4,-3) and (-2,5), we need to find the midpoint.\r
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\n" ); document.write( "\n" ); document.write( "X-Coordinate of Midpoint = \"%28x%5B1%5D%2Bx%5B2%5D%29%2F2+=+%284%2B-2%29%2F2=2%2F2+=+1\"\r
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\n" ); document.write( "\n" ); document.write( "Since the x coordinate of midpoint is \"1\", this means that \"h=1\"\r
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\n" ); document.write( "\n" ); document.write( "Y-Coordinate of Midpoint = \"%28y%5B1%5D%2By%5B2%5D%29%2F2+=+%28-3%2B5%29%2F2=2%2F2+=+1\"\r
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\n" ); document.write( "\n" ); document.write( "Since the y coordinate of midpoint is \"1\", this means that \"k=1\"\r
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\n" ); document.write( "\n" ); document.write( "So the center is the point (1, 1)\r
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\n" ); document.write( "\n" ); document.write( "Now let's find the radius squared\r
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\n" ); document.write( "\n" ); document.write( "Use the formula \"r%5E2=%28x-h%29%5E2%2B%28y-k%29%5E2\", where (h,k) is the center and (x,y) is an arbitrary point on the circle.\r
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\n" ); document.write( "\n" ); document.write( "In this case, \"h=1\" and \"k=1\". Also, \"x=4\" and \"y=-3\". Plug these values into the equation above and simplify to get:\r
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\n" ); document.write( "\n" ); document.write( "\"r%5E2=%284-1%29%5E2%2B%28-3-1%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"r%5E2=%283%29%5E2%2B%28-4%29%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"r%5E2=9%2B16\"\r
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\n" ); document.write( "\n" ); document.write( "\"r%5E2=25\"\r
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\n" ); document.write( "\n" ); document.write( "So because \"h=1\", \"k=1\", and \"r%5E2=25\", this means that the equation of the circle that passes through the points (4,-3) and (-2,5) (which are the endpoints of the diameter) is \r
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\n" ); document.write( "\n" ); document.write( "\"%28x-1%29%5E2%2B%28y-1%29%5E2=25\".
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