document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=165454>Question 165454</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This is a math stars question I can't don't know how to tell my son how to get the answer.<BR>\n" );
document.write( "Faye has 20 feet of fencing to make a rectangular pen for her dog. what is the largest area that she can fence in? His teacher said answer is 25 square feet-how did she get that answer? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #121940 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><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=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=121940\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the largest area enclosed by a rectangle is actually a square<BR>\n" );
document.write( "__ a square with a perimeter of 20ft has four 5ft sides<BR>\n" );
document.write( "__ so the area is 25sqft\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "to get technical __ the perimeter is 20ft, so L+W=10 (half the perimeter) __ L=10-W\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "the area is L times W __ A=L*W __ substituting A=(10-W)*W __ A=10W-W^2\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "A=-W^2+10W is a downward opening parabola __ the maximum value for A occurs at the axis of symmetry\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "the equation for the axis of symmetry is W=-(10)/(2*(-1)) __ W=5\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "substituting __ L+(5)=10 __ L=5\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "A=L*W __ A=5*5 __ A=25 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );