document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=353868>Question 353868</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The vertices of a Quadrilateral ABCD has coordinates A (-1,5)   b(7,1) <BR>\n" );
document.write( " C(5, -3)  and D(-3,1)\r<BR>\n" );
document.write( "\n" );
document.write( "show that the quadrilateral is  a rectangle </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #252965 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=252965\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> HI,  <BR>\n" );
document.write( "*Note: showing the quadrilateral ABCD has all four interior angles 90° (right angles) can be done by showing the adjacent sides <BR>\n" );
document.write( "are perpendicular to on another, by showing the slopes of the lines containing their respective coordinates are negative reciprocals.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "using the point-slope form:<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m+=%28y%5B2%5D+-+y%5B1%5D%29%2F%28x%5B2%5D+-+x%5B1%5D%29 ALIGN=MIDDLE  ALT=\"m+=%28y%5B2%5D+-+y%5B1%5D%29%2F%28x%5B2%5D+-+x%5B1%5D%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ".<BR>\n" );
document.write( "A (-1,5)   B(7,1)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m+=%281-+5%29%2F%287+-+%28-1%29%29=+%28+-1%2F2%29 ALIGN=MIDDLE  ALT=\"m+=%281-+5%29%2F%287+-+%28-1%29%29=+%28+-1%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "B(7,1) C(5, -3)<BR>\n" );
document.write( " <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m+=%28%28-3%29-+1%29%2F%285+-+7%29=+2 ALIGN=MIDDLE  ALT=\"m+=%28%28-3%29-+1%29%2F%285+-+7%29=+2\"   DISABLED_style= \"max-width:90%; height:auto;\" >. <BR>\n" );
document.write( "AB IS PERPENDICULAR TO BC<BR>\n" );
document.write( ".<BR>\n" );
document.write( "C(5, -3)  D(-3,1)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m+=%281+-%28-3%29%29%2F%28-3+-+5%29=+%28-1%2F2%29 ALIGN=MIDDLE  ALT=\"m+=%281+-%28-3%29%29%2F%28-3+-+5%29=+%28-1%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "BC IS PERPENDICULAR TO CD <BR>\n" );
document.write( ".<BR>\n" );
document.write( "D(-3,1)  A (-1,5) <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=m+=%285+-1%29%2F%28-1+-+4%29=+2 ALIGN=MIDDLE  ALT=\"m+=%285+-1%29%2F%28-1+-+4%29=+2\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "DA IS PERPENDICULAR TO AB </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );