document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=966148>Question 966148</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove that the exterior angle of a regular decagon is one - third the interior angle of a regular Pentagon. <BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #590514 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=590514\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the exterior angle of a decagon is equal to 360/10 = 36 degrees.\r<BR>\n" );
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document.write( "the internal angle of a pentagon is equal to 180 - 360/5 which is equal to 180 - 72 degrees which is equal to 108 degrees.\r<BR>\n" );
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document.write( "3 * 36 is equal to 108 degrees.\r<BR>\n" );
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document.write( "the exterior angle of a decagon is equal to 1/3 the interior angle of a pentagon.\r<BR>\n" );
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document.write( "these are all regular polygons, by the way.\r<BR>\n" );
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document.write( "the formulas only work with regular polygons.\r<BR>\n" );
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document.write( "the exterior angle of a pentagon is equal to 360/n, where n is the number of siges.\r<BR>\n" );
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document.write( "the interior angle of a polygon can be found by either one of the following formulas:\r<BR>\n" );
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document.write( "interior angle = (n-2) * 180 / n\r<BR>\n" );
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document.write( "interior angle = 180 - exterior angle.\r<BR>\n" );
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document.write( "for the pentagon, the first formula will become 3 * 180 / 5 = 3 * 36 = 108.\r<BR>\n" );
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document.write( "for the pentagon, the second formula will becomes 180 - 360/5 = 180 - 72 = 108.\r<BR>\n" );
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document.write( "you can take your pick as to which one is easier to work with.\r<BR>\n" );
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document.write( "from my perspective, the exterior angle formula is easier to remember.\r<BR>\n" );
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document.write( "exterior angle = 360 / n.\r<BR>\n" );
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document.write( "the interior angle of a polygon is always supplementary to the exterior angle of the same polygon.\r<BR>\n" );
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document.write( "interior angle = 180 - exterior angle.\r<BR>\n" );
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