document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=72592>Question 72592</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If angle 1 and angle 3 are supplementary, is triangle ABC iscoscles?  I say yes but how do I prove it? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #51900 by </B><A HREF=/tutors/aboutme.mpl?userid=bucky><B>bucky(2189)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=bucky><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=51900\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Think about this a minute!<BR>\n" );
document.write( ".<BR>\n" );
document.write( "If angle 1 and angle 3 are supplementary, what is their sum? (Use the definition of supplementary.)<BR>\n" );
document.write( ".<BR>\n" );
document.write( "What is the sum of the three angles of a triangle?<BR>\n" );
document.write( ".<BR>\n" );
document.write( "What has to be the measure of angle 2 in the triangle?<BR>\n" );
document.write( ".<BR>\n" );
document.write( "A more appropriate question than, \"is the triangle isosceles?\" would have been \"is there a triangle.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Now that you've thought about it a bit, angles 1 and 3 by being supplementary add up to<BR>\n" );
document.write( "180 degrees by definition.  The three angles of a triangle add up to be 180 degrees.<BR>\n" );
document.write( "So the \"third\" angle of the triangle would have to be 0 degrees so that when it is added<BR>\n" );
document.write( "to the supplementary angles the sum does not go over 180 degrees.  And if one of the angles<BR>\n" );
document.write( "of a triangle is zero degrees, you really don't have a triangle at all.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Hope this helps you to understand this problem a little better.  If you still can't see<BR>\n" );
document.write( "it, try this as an exercise.  Two right angles are supplementary.  Try making a triangle<BR>\n" );
document.write( "where two of the angles are 90 degrees.  Maybe that will give you some further insight into<BR>\n" );
document.write( "the problem.\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );