document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1129844>Question 1129844</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me prove the following proof: <BR>\n" );
document.write( "Given: Quadrilateral ABCD<BR>\n" );
document.write( "Prove: Measure of angle A + measure of angle B + measure of angle C + measure of angle D = 360 degrees<BR>\n" );
document.write( "There's a diagram that goes with it but i don't know how to show that </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #746470 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=746470\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=\"black\" face=\"times\" size=\"3\"><BR>\n" );
document.write( "One way to do this is to split the quadrilateral into two pieces as shown below<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" src = \"https://i.imgur.com/PhZMORb.png\"><BR>\n" );
document.write( "Recall that the sum of the three angles of any triangle is always 180 degrees. <BR>\n" );
document.write( "For each triangle, we can say<BR>\n" );
document.write( "A+B+C = 180<BR>\n" );
document.write( "D+E+F = 180<BR>\n" );
document.write( "If we add up the two sides of the equations above, then we get<BR>\n" );
document.write( "(A+B+C)+(D+E+F) = 180+180<BR>\n" );
document.write( "(A+D)+B+(C+F)+E = 360<BR>\n" );
document.write( "Which shows that the four angles add up to 360 regardless of what kind of quadrilateral we're working with<BR>\n" );
document.write( "</font> </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );