← All problems

Sum of Squares of Cosines

Trigonometry 1583
Compute $$\sum_{k=0}^{2024}\cos^2\!\left(\frac{(2k+1)\pi}{20}\right)$$The answer is in the form $\frac{\alpha}{\beta}$ for coprime integers $\alpha$ and $\beta$. Input the answer as the sum $\alpha +\beta$.