10th Eötvös Competition 1903

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1.  Prove that 2p-1(2p - 1) is perfect when 2p - 1 is prime. [A perfect number equals the sum of its (positive) divisors, excluding the number itself.]
2.  α and β are real and a = sin α, b = sin β, c = sin(α+β). Find a polynomial p(x, y, z) with integer coefficients, such that p(a, b, c) = 0. Find all values of (a, b) for which there are less than four distinct values of c.
3.  ABCD is a rhombus. CA is the circle through B, C, D; CB is the circle through A, C, D; CC is the circle through A, B, D; and CD is the circle through A, B, C. Show that the angle between the tangents to CA and CC at B equals the angle between the tangents to CB and CD at A.

 

The original problems are in Hungarian. They are available on the KöMaL archive on the web. They are also available in English (with solutions in): (Translated by Elvira Rapaport) József Kürschák, G Hajós, G Neukomm & J Surányi, Hungarian Problem Book 1, 1894-1905, MAA 1963. Out of print, but available in some university libraries.

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John Scholes
jscholes@kalva.demon.co.uk
20 Oct 1999
Last corrected/updated 30 Oct 03