SOLUTION: 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 ?

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 ?
Answer by ikleyn(52778) (Show Source): You can put this solution on YOUR website!
.

Had all 10 points be in general position (such that no three of them are collinear), we would have  =  = 45 different straight lines.

From this amount we need subtract  =  = 6 lines connecting collinear points pairly, and replace them by only one single line.


So, the answer is 45 - 6 + 1 = 40 lines.


Answer.  There are 40 different straight lines connecting given 10 points.

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