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		The figure shows an arbelos ABC (AB, BC, and AC are semicircles 
				of centers O1, O2, and O). The semicircles 
				of diameters AO2 (center O3) and CO1 (center O4)meet at E. BD is perpendicular to AC, 
				AD intersects semicircles O1 and O3 at A1 
				and A3, respectively, CD intersects semicircles O2 and O4 at C2 and 
				C4, respectively. Prove that (1) B, E, D are 
				collinear points; (2) A1C2 is 
				the common tangent to semicircles O1 and O2 at A1 and C2, 
				respectively; (3) A3C4 is the common tangent to 
				semicircles O3 
				and O4 at A3 and C4, respectively; 
				(4) A3 is the midpoint of DA1 and C4 
				is the midpoint of DC2; (5) M is the midpoint of A3C4; (6) A3C4 
				// A1A2; (7) A1C2 
				= BD = 2A3C4. See also:
				Artwork Problem 
				1071.
 
				 
 
 
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