Determine the principal stresses and$-$maximum in$-$plane shear stresses at Points A and $B$ of the below circular hollow section pipe. $P$ is a singe load in $y$ direction and $T$ is a torque about $x$ axis.

Hint: You need to first convert external loads to internal stresses at points A and B$.$ Then, use stress transformation concept to work out in$-$plane principal and maximum shear stresses. You can use either stress transformation equations or Mohr's circle.

$P=50kN$

$T=3kN.m$

$t=5mm$