Drill Class Problem $7\mathrm{.}1($combined stress problem$)$: The steel pipe $AB$ has a $102$ mm OD and a $6$ mm wall thickness. Knowing that arm CD is rigidly attached to the pipe; determine the principal stress and the maximum shear stress at point H and K $.$ Determine the factor with of safe respect to yield of the pipe, using $($a$)$ maximum shearing stress criterion, and $($b$)$ the maximum distortion energy criterion.