50-> 150 50 50° 150

A geotechnical engineer is evaluating the stability of a silty sand slope as shown. This evaluation is considering the potential for a shear failure at an infinitesimal point (soil element) on the trial shear surface. 
At this point, the soil is subjected to a major principal stress of +150 kN/m^2 and a minor 
principal stress of +50 kN/m^2
(A) Using the Pole Method, find the intensity of the normal and shear stresses acting on the shear plane making a 50 deg angle with the major principal plane of the infinitesimal element of soil. (Plot the Mohr circle) 
(B) If the silty sand is found to have a cohesion of 250 kPa and a friction angle of 25 deg from direct shear (DS) testing, plot the failure envelope against the same pole-method graphical construction completed under question above. 
(C) Determine the factor of safety (FOS) against potential landsliding at this same point on the shear surface