Radius $12$ cm, arc $14$ cm. The angle at the centre is approximately —

From $s=\frac{\pi r\theta}{180°}$, solving for the angle gives $\theta=\frac{180°\times s}{\pi r}=\frac{180\times 14}{\pi\times 12}\approx 66.84°$. The arc and radius determine the central angle.