document.write( "Question 1148509: How many distinct line segments are formed by connecting 20 collinear points? \n" ); document.write( "

Algebra.Com's Answer #769864 by ikleyn(52788) $\"\"$ $\"About$

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document.write( "Each segment is uniquely defined by a pair of its ending points;\r\n" );
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document.write( "and inversely, each pair of ending points uniquely determines the segment.\r\n" );
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document.write( "Here the pairs of ending points are considered as unordered pairs.\r\n" );
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document.write( "So, the number of segments is equal to the number of unordered pairs of 20 points, which is\r\n" );
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document.write( "     = 10*19 = 190.     ANSWER\r\n" );
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