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PnC. Number of quadrilaterals formed from collinear and non-collinear points.


There are 25 points on a plane of which 7 are collinear . How many quadrilaterals can be formed from these points ?


05-Sep-2015 1:33 PM
~8

Answers (1)


0

A quadrilateral is formed from 4 points where at most 2 can be colinear.

So, from total subtract unwanted possibilities

(Total ways) - (ways to pick 4 colinear points) - (ways to pick 3 colinear points)

ans = 25C4 - 7C4 - 7C3 . 18C1



05-09-2015 13:43
~48

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