document.write( "Question 1008377: find standard equation of circle that has centre on the line 5x-2y= -21 and tangent to both co-ordinate axes
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Algebra.Com's Answer #624103 by ikleyn(52802) $\"\"$ $\"About$

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\n" ); document.write( "find standard equation of a circle that has the center on the line 5x-2y= -21 and tangent to both co-ordinate axes.
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document.write( "Notice that the center of this circle lies on the bisector of the first quadrant angle, which is the line y = x.\r\n" );
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document.write( "So, the center is the intersection point of the straight line 5x - 2y = -21 and the straight line y = x.\r\n" );
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document.write( "In other words, to find the center, we should find the point on the line 5x - 2y = -21 with x = y. It has \r\n" );
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document.write( "the coordinates (a,a) such that 5a - 2a = -21. Hence, 3a = -21 and a = -7. Thus the center is (-7,-7).\r\n" );
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document.write( "Then the equation of the circle is \r\n" );
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document.write( " = ,\r\n" );
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document.write( "or\r\n" );
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document.write( " = .\r\n" );
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document.write( "It is not the unique solution.\r\n" );
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document.write( "The other solution can be found if another bisector y = -x of the II-IV quadrants is used. \r\n" );
document.write( "I don't want to go to this matter, but you can, if you want.\r\n" );
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