document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1118689>Question 1118689</A>: <I><SPAN STYLE=\"word-break: break-all;\"> ABCD is a trapezium in which AB is parallel to DC. The bisectors of angles A and D intersect at E. Prove that angle AED=90 degrees. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #734089 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=734089\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "Since AB and CD are the parallel sides, angles A and D are consecutive angles with an angle sum of 180 degrees.<br><BR>\n" );
document.write( "Since AE bisects angle A and DE bisects angle D, the sum of angles EAD and EDA is half of 180 degrees, or 90 degrees.<br><BR>\n" );
document.write( "In triangle ADE that means angle AED is 90 degrees. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );