document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1157225>Question 1157225</A>: <I><SPAN STYLE=\"word-break: break-all;\"> As I left collage 60 years ago my mathematics is rusty.  I want to build a solar cooker with the dimensions as follows:<BR>\n" );
document.write( "Diameter = 24 inches<BR>\n" );
document.write( "Focus point is 6 to 8 inches. \r<BR>\n" );
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document.write( "What I have tried. F(Y) = 4aX^2  where a the focus of 6 inches. However when I plot it all the lines are linear. <BR>\n" );
document.write( "thanks   Dave <BR>\n" );
document.write( "  email address    brotherdave@rogers.com </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #780055 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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/cgi-bin/show-face.mpl?user=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=780055\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Try <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+y%5E2+=+4a%2Ax+ ALIGN=MIDDLE  ALT=\"+y%5E2+=+4a%2Ax+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The focus will be on the x-axis a units from the origin.<BR>\n" );
document.write( "here's the plot with <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+5+ ALIGN=MIDDLE  ALT=\"+a+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" >:<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+graph%28+500%2C+500%2C+-12%2C+12%2C+-12%2C+12%2C+sqrt%28+20x+%29%2C+-sqrt%28+20x+%29%29+ ALIGN=MIDDLE  ALT=\"+graph%28+500%2C+500%2C+-12%2C+12%2C+-12%2C+12%2C+sqrt%28+20x+%29%2C+-sqrt%28+20x+%29%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "A vertical line through the focus intersects the parabola at<BR>\n" );
document.write( "( a, 4a/2 ) and ( a, -4a/2 ), and with <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+5+ ALIGN=MIDDLE  ALT=\"+a+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "( 5, 10 ) and ( 5, -10 )<BR>\n" );
document.write( "You can use <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+ ALIGN=MIDDLE  ALT=\"+a+\"   DISABLED_style= \"max-width:90%; height:auto;\" > to adjust diameter of the ( rotated ) parabola <BR>\n" );
document.write( "which is the cooker.<BR>\n" );
document.write( "Note that solving for <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+y+ ALIGN=MIDDLE  ALT=\"+y+\"   DISABLED_style= \"max-width:90%; height:auto;\" >,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+y+=+sqrt%28+4a%2Ax+%29+ ALIGN=MIDDLE  ALT=\"+y+=+sqrt%28+4a%2Ax+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > and<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+y+=+-sqrt%28+4a%2Ax+%29+ ALIGN=MIDDLE  ALT=\"+y+=+-sqrt%28+4a%2Ax+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "---------------------------<BR>\n" );
document.write( "hope this helps\r<BR>\n" );
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document.write( " </SPAN>\n" );
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