MathDB

B3

Part of 1974 Putnam

Problems(1)

Putnam 1974 B3

Source: Putnam 1974

5/28/2022
Prove that if aa is a real number such that cos⁡πa=13,\cos \pi a= \frac{1}{3}, then aa is irrational.
Putnamirrationalcosine