please answer all parts and explain fully, this is for study purposes so concepts matter. thank you!!!

$(35)$ A fixed, angled member with a solid square cross$-$section is subjected to the loads shown in Fig. P$4$a$.$ The stresses at the cross$-$section at $\backslash ($ A $\backslash )$ are of interest in this design. Points $\backslash ($ A$,$ B $\backslash )$ and $\backslash ($ C $\backslash )$ are located at centerlines of the shaft. Use the following dimensions and loads:

Length between $\backslash ($ A $\backslash )$ and $\backslash ($ B $\backslash )$ : $\backslash ($ L$\_\{$A B$\}=500\backslash$mathrm$\{$~mm$\}\backslash )$

Length between $\backslash ($ B $\backslash )$ and $\backslash ($ C: L$\_\{$B C$\}=150\backslash$mathrm$\{$~mm$\}\backslash )$

Cross$-$section dimensions of member: $\backslash ($ a$=$b$=20\backslash$mathrm$\{$~mm$\}\backslash )$

Axial load: $\backslash ($ P$=1200\backslash$mathrm$\{$~N$\}\backslash ),$ Vertical load: $\backslash ($ F$=400\backslash$mathrm$\{$~N$\}\backslash )$

Figure P$4($a$)$ Fixed, angled member and $($b$)$ cross$-$section at A$.$

a$.$ Determine the internal loads at the cross$-$section at A$.$ In your answer, be clear which direction each force is acting in and which axis each moment$/$torque is acting around.

b$.$ On the cross$-$section shown in Fig. P$4$b$,$ which point is the critical point of interest? Assume stress from bending is much larger than transverse shear stress. Neglect stress concentrations.

Circle one: Point D or Point $\backslash ($ E $\backslash )$

c$.$ Explain in one grammatically$-$correct sentence why you chose that point as critical.

d$.$ Determine the stresses at point $\backslash ($ D $\backslash )$ and present your answer in matrix form. Do not forget to include units.

e$.$ Using your answers to $($d$),$ determine the ordered principal stresses.

f$.$ Using your answer to $($e$),$ determine the maximum shear stress, $\backslash (\backslash$tau$\_\{\backslash$text $\{$max $\}\}\backslash ).$

g$.$ When considering yield criteria, can this state of stress determined in part $($c$)$ be considered 'special case'?

h$.$ If the chosen material is Aluminum $2014-$T$6,$ determine the safety factor based on the stresses calculated in part $($c$)$ using:

i$.$ Tresca yield criterion

ii$.$ Von Mises yield criterion