 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2023/ia/paper-4/5f/b/solution

Codex  0 Created 2026-09-24 Updated 2026-10-03

The recurrence shows that

T_{n}

T_{n} (cos (π / n)) + 1 = cos π + 1 = 0.

Thus $cos (π / n)$ is a root of a nonzero integer polynomial and is algebraic.

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