olymmath

NO-ABEL 2013

Abel Competition 2013.

Other problems

Problem 2

In a triangle TT , all the angles are less than 90o90^o , and the longest side has length ss . Show that for every point pp in TT we can pick a corner hh in TT such that the distance from pp to hh is less than or equal to s/3s/\sqrt3 .

Problem 3

A prime number p≥5p \ge 5 is given. Write 13+24+...+p−3p−1=ab\frac13+\frac24+... +\frac{p -3}{p - 1}=\frac{a}{b} for natural numbers aa and bb . Show that pp divides aa .