document.write( "Question 54724: How many diagonal lines are there in a 130-sided polygon? \n" ); document.write( "
Algebra.Com's Answer #36944 by Edwin McCravy(20056)\"\" \"About 
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How many diagonal lines are there in a 130-sided \r\n" );
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document.write( "The set of all pairs of vertices includes all the \r\n" );
document.write( "diagonals plus all of the 130 sides.  So to find \r\n" );
document.write( "the number of diagonals, we calculate the number \r\n" );
document.write( "of combinations of 130 vertices taken 2 at a time \r\n" );
document.write( "and then subtract the 130 sides.  So the answer is\r\n" );
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document.write( "C(130,2) - 130 =\r\n" );
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document.write( "130·129/2·1 - 130 =\r\n" );
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document.write( "8385 - 130 =\r\n" );
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document.write( "8255 diagonal lines\r\n" );
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document.write( "Edwin
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