For the state of plane stress shown, determine (a) the largest value of sigma_y for which the maximum in-plane shear stress is equal to or less than 21 ksi. (b) the corresponding principal stresses....

For the state of plane stress shown, determine (a) the largest value of sigma_y for which the maximum in-plane shear stress is equal to or less than 21 ksi. (b) the corresponding principal stresses. Assume stress magnitudes of S_x = 36 ksi and S_xy = 13 ksi. Answers: (a) sigma_y = 3.015 ksi (b) sigma_p1 = 36.107 kis sigma_p2 = 2.09 ksi