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				In the figure above, ABCD is a 
				trapezoid of area S with AD parallel to BC and E the point of intersection of the diagonals AC and BD. If S1, 
				S2, 
				S3, and S4 
				are the areas of triangles BEC, AED, ABE, and CED respectively, 
				(1) prove that
				 , 
				and (2) prove that  .
				See also: Problem 
				163. |