document.write( "Question 898741: Each interior angle of a regular polygon is thrice each exterior angle.
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Algebra.Com's Answer #544981 by Edwin McCravy(20056)\"\" \"About 
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Each interior angle of a regular polygon is thrice each exterior angle.
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document.write( "An interior angle and an exterior angle at a vertex of a polygon\r\n" );
document.write( "are supplementary.\r\n" );
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document.write( "Let the exterior angle be X.\r\n" );
document.write( "Then the interior angle is 3X.\r\n" );
document.write( "Since they are supplementary,\r\n" );
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document.write( "X + 3X = 180°\r\n" );
document.write( "    4X = 180°\r\n" );
document.write( "     X = 45°\r\n" );
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document.write( "So each exterior angle is 45°, and each interior angle is 3×45°=135°.\r\n" );
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document.write( "Let the number of sides be N.\r\n" );
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document.write( "The sum of the exterior angles of a polygon is 360°\r\n" );
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document.write( "Since the polygon is regular, each interior angle is \"%22360%B0%22%2FN\"\r\n" );
document.write( "So\r\n" );
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document.write( "\"%22360%B0%22%2FN\"\"%22%22=%22%22\"\"%2245%B0%22\"\r\n" );
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document.write( "Multiply both sides by N\r\n" );
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document.write( "\"%22360%B0%22\"\"%22%22=%22%22\"\"%2245%B0%22N\"\r\n" );
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document.write( "Divide both sides by 45°\r\n" );
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document.write( "\"8\"\"%22%22=%22%22\"\"N\"\r\n" );
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document.write( "It's an 8-sided regular polygon, a regular octagon.\r\n" );
document.write( "In the regular octagon below, the 135° angle is an INTERIOR angle,\r\n" );
document.write( "and the 45° angle is an exterior angle.  \r\n" );
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document.write( "Edwin
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