document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=624775>Question 624775</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given:<BR>\n" );
document.write( "Angle 1 is congruent to angle 3. <BR>\n" );
document.write( "Prove:<BR>\n" );
document.write( "Angle 2 is congruent to angle 4.\r<BR>\n" );
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document.write( "*Angle 1 and 2 are vertical angles.<BR>\n" );
document.write( " Angle 3 and 4 are vertical angles. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #393042 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=393042\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Angles 1 and 2 are vertical angles. So angle 1 = angle 2 because vertical angles are congruent.\r<BR>\n" );
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document.write( "Angles 3 and 4 are vertical as well. So angle 3 = angle 4 by the same reason.\r<BR>\n" );
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document.write( "Since it's given that \"Angle 1 is congruent to angle 3. \", this also means that angle 1 = angle 3\r<BR>\n" );
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document.write( "Now we can use substitution to get\r<BR>\n" );
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document.write( "angle 1 = angle 3\r<BR>\n" );
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document.write( "angle 2 = angle 3  << -- replace \"angle 1\" with \"angle 2\" (since the two are congruent)\r<BR>\n" );
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document.write( "angle 2 = angle 4  << -- replace \"angle 3\" with \"angle 4\" (since the two are congruent)\r<BR>\n" );
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document.write( "So because we've shown that angle 2 = angle 4 , this proves Angle 2 is congruent to angle 4 </SPAN>\n" );
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