The possible slip surface has a radius equal to 22 m, and passing through the toe of cut slope and trough the point 3.6 m away on the top ground from the edge of cut. The C.G of failure mass is 10.3 m from the center of failure circle. The properties of soil are C = 50 kN/m$^{2}$, $\phi=15^{\circ}$ has $\gamma$=18 kN/m$^{3}$. Find the factor of safety that would be available in slip surface. Use friction circle method.