document.write( "Question 1076714: Find an equation of the circle that passes through the points (2,3), (4,5), and (0,-3). \n" ); document.write( "
Algebra.Com's Answer #691338 by MathLover1(20850)\"\" \"About 
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Find an equation of the circle that passes through the points (\"2\",\"3\"), (\"4\",\"5\"), and (\"0\",\"-3\"). \r
\n" ); document.write( "\n" ); document.write( "The standard form equation of a circle is \"+%28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2\" where\r
\n" ); document.write( "\n" ); document.write( "\"h\" and \"k\" are the \"x\" and \"y\" coordinates of the center of the circle \r
\n" ); document.write( "\n" ); document.write( "first find coordinates of the center (\"h\",\"k\") using given points\r
\n" ); document.write( "\n" ); document.write( "The first step is to set up these 3 equations by plugging the x- and y-coordinates of the points
\n" ); document.write( "(\"2\",\"3\"), (\"4\",\"5\"), and (\"0\",\"-3\") into the circle formula:\r
\n" ); document.write( "\n" ); document.write( "\"%282+-+h%29%5E2+%2B+%283+-+k%29%5E2+=+r%5E2\".................eq1
\n" ); document.write( "\"%284+-+h%29%5E2+%2B+%285+-+k%29%5E2+=+r%5E2\"..................eq2
\n" ); document.write( "\"%280+-+h%29%5E2+%2B+%28-3+-+k%29%5E2+=+r%5E2\".................eq3
\n" ); document.write( "----------------------------------------------\r
\n" ); document.write( "\n" ); document.write( "\"h%5E2+-+4+h+%2B+k%5E2+-+6+k+%2B+13+=+r%5E2\".................eq1
\n" ); document.write( "\"h%5E2+-+8+h+%2B+k%5E2+-+10+k+%2B+41=+r%5E2\"..................eq2
\n" ); document.write( "\"h%5E2+%2B+k%5E2+%2B+6+k+%2B+9+=+r%5E2\"...............eq3\r
\n" ); document.write( "\n" ); document.write( "--------------------------------------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"h%5E2+-+4+h+%2B+k%5E2+-+6+k+%2B+13+=+r%5E2\".................eq1
\n" ); document.write( "\"h%5E2+-+8+h+%2B+k%5E2+-+10+k+%2B+41=+r%5E2\"..................eq2...............subtract eq2 from eq1
\n" ); document.write( "---------------------------------------------------------
\n" ); document.write( "\"h%5E2+-+4+h+%2B+k%5E2+-+6+k+%2B+13-%28h%5E2+-+8+h+%2B+k%5E2+-+10+k+%2B+41%29=+r%5E2-r%5E2\"
\n" ); document.write( "\"h%5E2+-+4+h+%2B+k%5E2+-+6+k+%2B+13-h%5E2+%2B8+h-+k%5E2+%2B10+k+-+41=+0\"
\n" ); document.write( "\"4+h+%2B+4+k+-+28=+0\"............simplify
\n" ); document.write( "\"+h+%2B++k+-+7=+0\".............eq1a\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "h^2 - 4h + k^2 - 6 k + 13 = r^2.................eq1
\n" ); document.write( "h^2 + k^2 + 6k + 9 = r^2...............eq3...........subtract eq3 from eq1
\n" ); document.write( "------------------------------------------
\n" ); document.write( "\"h%5E2+-+4h+%2B+k%5E2+-+6k+%2B+13++-%28h%5E2+%2B+k%5E2+%2B+6+k+%2B+9+%29=+r%5E2-r%5E2\"
\n" ); document.write( "\"h%5E2+-+4h+%2B+k%5E2+-+6k+%2B+13++-h%5E2+-+k%5E2+-+6+k+-+9+=0\"
\n" ); document.write( "\"-4+h+-+12k+%2B+4+=0\"............divide by -4
\n" ); document.write( "\"+h+%2B3k+-+1+=0\"..............................eq2a\r
\n" ); document.write( "\n" ); document.write( "use
\n" ); document.write( " \"h+%2B++k+-+7=+0\"...............eq1a
\n" ); document.write( " \"+h+%2B3+k+-+1+=0\"..............................eq2a
\n" ); document.write( "-------------------------------------------------------------subtract eq1a from eq2a\r
\n" ); document.write( "\n" ); document.write( "\"+h+%2B3+k+-+1+-%28h+%2B++k+-+7%29=0\"\r
\n" ); document.write( "\n" ); document.write( " \"h+%2B3+k+-+1+-h+-++k+%2B+7=0\"\r
\n" ); document.write( "\n" ); document.write( "\"2+k++%2B+6=0\"\r
\n" ); document.write( "\n" ); document.write( "\"2+k++=-6\"\r
\n" ); document.write( "\n" ); document.write( "\"+highlight%28k++=+-3%29\"\r
\n" ); document.write( "\n" ); document.write( "now find \"h\"\r
\n" ); document.write( "\n" ); document.write( " \"h+%2B++k+-+7=+0\"...............eq1a\r
\n" ); document.write( "\n" ); document.write( " \"h+-3-+7=+0\"\r
\n" ); document.write( "\n" ); document.write( "\"h-10=0\"\r
\n" ); document.write( "\n" ); document.write( "\"h=10\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "so, center is at (\"10\",\"-3\")\r
\n" ); document.write( "\n" ); document.write( "use one point, h and k to find r\r
\n" ); document.write( "\n" ); document.write( "\"%282+-+10%29%5E2+%2B+%283+-+%28-3%29%29%5E2+=+r%5E2\".................eq1\r
\n" ); document.write( "\n" ); document.write( "\"%28+-+8%29%5E2+%2B+%283+%2B3%29%5E2+=+r%5E2\"\r
\n" ); document.write( "\n" ); document.write( "\"64+%2B+36+=+r%5E2\"\r
\n" ); document.write( "\n" ); document.write( " \"r%5E2=100\"\r
\n" ); document.write( "\n" ); document.write( "\"r=10\"\r
\n" ); document.write( "\n" ); document.write( "and, your equation is:\r
\n" ); document.write( "\n" ); document.write( " \"%28x-10%29%5E2%2B%28y%2B3%29%5E2=10%5E2\"\r
\n" ); document.write( "\n" ); document.write( "(2,3), (4,5), and (0,-3).
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