Problem $1(20$ Points$)$:

The drill is jammed in the wall and is subjected to the torque and force:

A$.$ Determine the state of stress at point $A$ on the cross section of the drill bit at section $a-$a;

B$.$ Determine the state of stress at point B on the cross section of the drill bit at section $a-$a$.$

Hint: use rational graphical methods and$/$or appropriate element $($cube$)$ to explain the stress state.