how many lines can be drawn from 10 points out of which 4 points are collinear?

Asked by Jaahnvi | 9th Jun, 2013, 02:46: PM

Expert Answer:

Straight line can be formed by joining 2 points

so number of ways in which we can select 2 points from 10 points is  = 10C2

 but it also include that in which 4 points are in straight line . from those 4 points only one line can be formed .

so we have to subtract 4C2 -1 from above result

Therefore, total number of lines = 10C2   - 4C2 + 1 = 45 - 6 + 1 = 40

Answered by  | 9th Jun, 2013, 02:53: PM

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