document.write( "Question 1107104: A circle with centre (2,-3) has a tangent of 24x+7y-12=0. Find the equation of the circle\r
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Algebra.Com's Answer #722095 by Edwin McCravy(20054)\"\" \"About 
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A circle with centre (2,-3) has a tangent of 24x+7y-12=0. Find the equation of the circle.
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document.write( "Here's the graph:\r\n" );
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document.write( "You have the center.  You need the radius, which is the green line.\r\n" );
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document.write( "What you need is the distance formula from a point to a line:\r\n" );
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document.write( "The perpendicular distance from the point (x1,y1)to the line\r\n" );
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document.write( "Ax+By+C=0 is\r\n" );
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document.write( "d = \"abs%28Ax%5B1%5D%2BBy%5B1%5D%2BC%29%2Fsqrt%28A%5E2%2BB%5E2%29\"\r\n" );
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document.write( "Your line is 24x+7y-12 = 0\r\n" );
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document.write( "So you plug in A=24, B=7, C=-12 and (x1,y1) = (2,-3)\r\n" );
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document.write( "Substitute that into the formula for d.  That will be the radius r.\r\n" );
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document.write( "Then substitute (h,k) = (2,-3) and that value of r into\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( "If you have any difficulty, tell me in the note form below and I'll\r\n" );
document.write( "get back to you by email.\r\n" );
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document.write( "Edwin
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