$*4\mathrm{.}141$ through $*4\mathrm{.}143$ The couple $M$ acts in a vertical plane and is applied to a beam oriented as shown. Determine the stress at point $A.$

$I_y=1\mathrm{.}894{10}^{6}m{m}^4$

$I_z=0\mathrm{.}614{10}^{6}m{m}^4$

$I_{yz}=+0\mathrm{.}800{10}^{6}m{m}^4$

Fig. P$4\mathrm{.}141$

Fig. P$4\mathrm{.}142$