If -Sn, a tetragonal crystal (point group 4/mmm, a = 0.583 nm, and c = 0.318 nm) is subject to a tensile stress of 63 MPa along [100] and to a shear stress of 18 MPa on the (100) plane in the [010] direction. Determine: a) the tensile stress normal to (110), and b) the shear stress on the (110) plane in the [1-10] direction.