Relative to a rectangular Cartesian coordinate system, a stress field is given by 2 σ₁₁ = (1-x²³)X₂+²X² 022 = and all other σ = 0 σ33 = (3-X²)X₂ 012021=-(4-x)X₁ a) Determine whether or not this stress field satisfies the equations of equilibrium under zero body force. Show all your calculations. b) Find σ, at the point with coordinates X-2, X2=-1, X3=6. c) Consider a plane described by 3X, +6X, +2X, =12 Determine the traction vector at the point given in the above (b). (Hint: Find the normal vector for the equation, 3X, +6X, +2X₁ = 12. Then find 1₁ =σ n =σn.)