document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=742955>Question 742955</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A designer of a 200-foot-diameter parabolic electromagnetic antenna for tracking space probes wants to place the focus 100 feet above the vertex. Find the equation of the parabola using the axis of the parabola as the y-axis and vertex as the origin then determine the depth of the parabolic reflector. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #452692 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39620)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=452692\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Textbook derivation should show a result of a basic parabola as <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4py=x%5E2 ALIGN=MIDDLE  ALT=\"4py=x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, where p is the distance from vertex to focus.  Your example uses p=100, so you have a parabola describing <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=4%2A100%2Ay=x%5E2 ALIGN=MIDDLE  ALT=\"4%2A100%2Ay=x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28y=%281%2F400%29x%5E2%29 ALIGN=MIDDLE  ALT=\"highlight%28y=%281%2F400%29x%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.  \r<BR>\n" );
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document.write( "The diameter of the antenna being 200 feet means that radius is 100 feet.  The is in the x direction.  To find how deep, use x=100 in the parabola's equation to find y, which will be how deep.  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=Depth=y=%281%2F400%29%28100%29%5E2 ALIGN=MIDDLE  ALT=\"Depth=y=%281%2F400%29%28100%29%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" >, depth is 25 feet. </SPAN>\n" );
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