document.write( "Question 936457: What is the equation of the directrix of the parabola given by the equation (y - 3)^2 = 8(x - 5)?
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Algebra.Com's Answer #569947 by Edwin McCravy(20059) $\"\"$ $\"About$

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document.write( "First we have to graph the parabola:\r\n" );
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document.write( "[Always draw graphs when doing conic section problems].\r\n" );
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document.write( "Compare it to \r\n" );
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document.write( "So the vertex is (h,k) = (5,3).\r\n" );
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document.write( "It opens to the right because 4a=8 or a=2 is positive.\r\n" );
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document.write( "So we sketch in the parabola with vertex (5,3).\r\n" );
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document.write( "|a|=2 is the distance from both the vertex to both the focus and the directrix.\r\n" );
document.write( "The focus is a point inside the parabola and the directrix is a line\r\n" );
document.write( "outside the parabola line, which are the green point and line drawn below:\r\n" );
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document.write( "So as we see from the graph, the focus is (7,3) and the directrix is x=3.\r\n" );
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document.write( "I went ahead and found the focus because in other problems you will have\r\n" );
document.write( "to find the focus.\r\n" );
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document.write( "Edwin

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