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						| Problem 258. 
						Equilateral Triangle, Incircle, Point, Vertices, 
						Side, Distances, Squares |  
						| 
              The figure shows an 
				equilateral triangle ABC. If a point D is on the incircle, DA = d, DB = e, DC = f, and
				AC = a, prove that
				 .
       
	View or post a solution. 
                
				 
 
 
See also:  
 
Median length, Apollonius' TheoremEuclid's Elements Book II Proposition 13
 Problem 
		257
 Problem 
256
 Equilateral Triangle
 
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