Problem 7-2 A plane element in a body is subject to a normal compressive stress in the x-direction of 60 MPa as well as a shearing stress of 40 MPa, as shown below. Find: (a) The normal and shearing stress intensities on a plane inclined at an angle of 30° to the normal stress. (b) The maximum and minimum values of the normal stress that may exist on inclined planes and the direction of these stresses. (c) The magnitude and direction of the maximum shearing stress that may exist on an inclined plane.