MathNet 2026 — Part 07 Question 64

Consider an acute triangle with angles $\alpha, \beta, \gamma$ opposite the sides $a, b, c$, respectively. If $\sin \alpha=\frac{3}{5}$ and $\cos \beta=\frac{5}{13}$, evaluate $\frac{a^{2}+b^{2}-c^{2}}{a b}$.