The normal stresses on two neutrally perpendicular planes are \(100 \mathrm{MPa}\) (tensile) and \(40 \mathrm{MPa}\) (compressive) together with shear stress of \(70 \mathrm{MPa}\). Determine graphically or otherwise,

(a) the magnitude and direction of principal stresses, and

(b) the magnitude of normal and shear stresses on a plane on which the shear stress is maximum.