The normal stresses at a point in an elastic material are 30 MPa(tensile) and 15 MPa

(compressive) respectively at right angle to each other with a shearing stress of 25 MPa.

Determine: (i) the principal stresses and position of principal planes, (ii) plane and magnitude of

maximum shear stress and (iii) direct and shear stresses at a plane inclined at an angle of 30o

with the plane of 30 MPa tensile stress.