A consolidated-drained triaxial test was conducted on a normally consolidated clay. The results are as follows: - Confining pressure, σ! = 250 kPa - Deviatoric stress at failure, (σ")# = 275 kPa Determine: (a) angle of friction ϕ′; (b) angle θ that the failure plane makes with the major principal plane; and (c) normal and shear stresses on the failure plane