Let be a triangle, and let , , be three points in the interiors of the sides , , of this triangle. Prove that the area of at least one of the three triangles , , is less than or equal to one quarter of the area of triangle .
Alternative formulation: Let be a triangle, and let , , be three points on the segments , , , respectively. Prove that
,
where the abbreviation denotes the (non-directed) area of an arbitrary triangle .
Alternative formulation: Let be a triangle, and let , , be three points on the segments , , , respectively. Prove that
,
where the abbreviation denotes the (non-directed) area of an arbitrary triangle .