document.write( "Question 826426: A parabola is defined as a set of points that are equidistant from a given line (called the directrix of the parabola) and a given point (called the focus) of the parabola.\r
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Algebra.Com's Answer #498080 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Every one of those vertical green lines from the curve down to the\r\n" );
document.write( "x-axis must be equal to the slanted line that it's connected to that\r\n" );
document.write( "goes to the point (0,2). Not only those but also an infinite number of \r\n" );
document.write( "possible pairs of green lines that COULD be drawn.\r\n" );
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document.write( "Let's pick one of those pairs of green line at random, and label it\r\n" );
document.write( "with the variable coordinates (x,y).  the bottom of the green line\r\n" );
document.write( "must have the same x-coordinate, so it has the coodinates (x,0).\r\n" );
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document.write( "We use the distance formula\r\n" );
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document.write( "d = √(x2-x1)²+(y2-y1)²\r\n" );
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document.write( "to set the distance from (x,y) to (x,0) equal to the distance between\r\n" );
document.write( "(x,y) to (0,2)\r\n" );
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document.write( "    √(x-x)²+(0-y)² = √(0-x)²+(2-y)² \r\n" );
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document.write( "Squaring both sides takes away the radicals\r\n" );
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document.write( "     (x-x)²+(0-y)² = (0-x)²+(2-y)²\r\n" );
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document.write( "        (0)²+(-y)² = (-x)²+(2-y)²\r\n" );
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document.write( "              0+y² = x²+(4-4y+y²)\r\n" );
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document.write( "                y² = x²+4-4y+y²\r\n" );
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document.write( "                 0 = x²+4-4y\r\n" );
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document.write( "                4y = x²+4\r\n" );
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document.write( "                 y = \"1%2F4\"x²+1\r\n" );
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document.write( "That's the equation.\r\n" );
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document.write( "Edwin
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