I need help with question 3. Thank you

1. Consider two coordinate systems (x, y, z) and (x', y', z') where the second one is obtained by rotation of the first one by angle a about the x-axis. V' a Find the components of [&'] in terms of the components and angle a. For simplicity, assume that tensor has only yy, yz, and zz non-zero components. 2. Show that the sum Eyy'tEzz' is the same in any x'y'z' system. 3. Find angle a for which the shear strain Ey'z'=0