Given
![5](/media/m/e/a/3/ea36c795dac330f34d395d8364d379b6.png)
points in the plane, no three of them being collinear. Show that among these
![5](/media/m/e/a/3/ea36c795dac330f34d395d8364d379b6.png)
points, we can always find
![4](/media/m/d/a/6/da6087359ae47e86dcb2e49565050046.png)
points forming a convex quadrilateral.
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Given $5$ points in the plane, no three of them being collinear. Show that among these $5$ points, we can always find $4$ points forming a convex quadrilateral.