$${\omega = \sqrt{\frac{3g}{L} (1 - \cos \theta)} = \sqrt{\frac{3(9,8\, \mathrm{m/s^2})}{55,0\, \mathrm{m}} (1 - \cos 35,0^{\circ})} \\ = \underline{\underline{0,311\, \mathrm{rad/s}}}}$$