document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1121389>Question 1121389</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Show that A(-2,4),B(2,0),C(2,8) and D(6,4) are the vertices of a square </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #737259 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=737259\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Draw this and start with AB, which has slope -1<BR>\n" );
document.write( "BD has slope 1, so their product is -1 and they are perpendicular.<BR>\n" );
document.write( "DC has slope -1 and CA has slope 1, so they are perpendicular.<BR>\n" );
document.write( "Drawing this and labelling it is important, because BC is not along the perimeter of the square but is a diagonal.<BR>\n" );
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