document.write( "Question 60757This question is from textbook
\n" ); document.write( ": Find the equation of the circle that passes through the origin and has its center at (-3,-4). \n" ); document.write( "

Algebra.Com's Answer #41723 by Edwin McCravy(20059) $\"\"$ $\"About$

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Find the equation of the circle that passes through the \r\n" );
document.write( "origin and has its center at (-3,-4).\r\n" );
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document.write( "The equation of a circle with center (h,k) and radius r is\r\n" );
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document.write( "(x - h)² + (y - k)² = r²\r\n" );
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document.write( "We do not know the radius r, but we do know h and k,\r\n" );
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document.write( "(h, k) = (-3, -4), so we have\r\n" );
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document.write( "(x + 3)² + (y + 4)² = r²\r\n" );
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document.write( "Now since we are told that the circle passes through the\r\n" );
document.write( "origin, then we can substitute (x, y) = (0, 0)\r\n" );
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document.write( "(x + 3)² + (y + 4)² = r²\r\n" );
document.write( "(0 + 3)² + (0 + 4)² = r²\r\n" );
document.write( "            3² + 4² = r²\r\n" );
document.write( "             9 + 16 = r² \r\n" );
document.write( "                 25 = r²\r\n" );
document.write( "                  5 = r\r\n" );
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document.write( "So the equation is\r\n" );
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document.write( "(x + 3)² + (y + 4)² = 5²\r\n" );
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document.write( "(x + 3)² + (y + 4)² = 25\r\n" );
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document.write( "Your teacher may want you to multiply that out and get\r\n" );
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document.write( "x² + y² + 6x + 8y = 0\r\n" );
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document.write( "Edwin

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