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Similar Sides Sought (Posted on 2005-06-20) Difficulty: 3 of 5
Find two similar triangles with sides (A,B,C) and (A,B,D), such that D-C=20141.

  Submitted by Old Original Oskar!    
Rating: 3.5000 (2 votes)
Solution: (Hide)
The only possibility is that C is the smallest side in the first triangle, and D the largest one in the second, and then K(C,A,B)=(A,B,D), so we get A=CK, B=AK, D=BK, and so D=CK³.

As sides are integers, K must be a rational = M/N, and CM³/N³ must be an integer. The sides C, A, B, D are then C, CM/N, CM²/N², CM³/N³.

Obviously N³ must divide C, so we can write C=EN³ and the sides are now EN³, EMN², EM²N, EM³. We have D-C=20141, so E(M³-N³)=20141.

Factoring, E(M-N)(M²+MN+N²)=11x1831, and the only way this works is with E=1, M-N=11 and M²+MN+N²=1831 (so M=30 and N=19) and the triangles are (6859, 10830, 17100) and (10830, 17100, 27000).

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Puzzle Thoughts K Sengupta2023-06-30 01:44:00
Solutionsolution - no spoilerpcbouhid2005-06-27 20:21:52
Solutionre: Almost there...I am thereBrian Smith2005-06-24 23:48:10
Some ThoughtsAlmost there...Federico Kereki2005-06-24 22:44:56
Questionre: BIG GOOFJer2005-06-22 19:00:45
BIG GOOFOld Original Oskar!2005-06-20 19:51:25
General SolutionJer2005-06-20 17:56:51
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