MathDB

Trigonometric function not of a special form

Source: Bulgarian MO 2007, Day 1, Problem 3

May 16, 2007

functiontrigonometryalgebrapolynomialsearchalgebra proposed

Problem Statement

Find the least positive integer

n

such that

\cos\frac{\pi}{n}

cannot be written in the form

p+\sqrt{q}+\sqrt[3]{r}

with

p,q,r\in\mathbb{Q}

.
O. Mushkarov, N. Nikolov
No-one in the competition scored more than 2 points