Student's proof ends 60 years of math puzzling

Two winners of the Andrew H. Brown Prize in Mathematics, Edward H. Friend ’47 and Andrei Negut ’08, met in Frist Campus Center in February to discuss Negut’s solution of a mathematical problem that had puzzled Friend since his time at Princeton. After learning that Negut had won the Brown prize, awarded to the outstanding junior in mathematics, Friend wrote to Negut to ask if he could provide “an elegant proof” of the following geometry problem, which Friend had been able to prove negatively but not positively: Build on any scalene triangle three triangles with base angles 30 degrees and then connect the vertices of these three triangles and prove the resulting triangle is equilateral. Six weeks later, Friend received a three-page proof from Negut, who said he had been “delighted” to take a break from his algebraic geometry studies. Friend described the exchange as “a link across 60 years of time and reflects the essence of what we have in common.”