A $13$ kN force is applied as shown to the $60$ mm diameter cast iron post ABD. At point H $,$ determine $($a$)$ the principal stresses and principal planes. $($b$)$ the maximum shearing stress. $($c$)$ Normal and tangential stresses in an oblique plane at an angle of $30$ with respect to minor axis. $($d$)$ Maximum and minimum principal strains and the shear strain.