document.write( "Question 1106357: 1)there are 10 poiots in a plane of which 4 are collinear. No three of the reamaining 6 points are collinear. How many different straight lines can be drawn by joining them ? \n" ); document.write( "
Algebra.Com's Answer #721332 by ikleyn(52781)\"\" \"About 
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document.write( "Had all 10 points be in general position (such that no three of them are collinear), we would have \"C%5B10%5D%5E2\" = \"%2810%2A9%29%2F%281%2A2%29\" = 45 different straight lines.\r\n" );
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document.write( "From this amount we need subtract \"C%5B4%5D%5E2\" = \"%284%2A3%29%2F%281%2A2%29\" = 6 lines connecting collinear points pairly, and replace them by only one single line.\r\n" );
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document.write( "So, the answer is 45 - 6 + 1 = 40 lines.\r\n" );
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document.write( "Answer.  There are 40 different straight lines connecting given 10 points.\r\n" );
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