The bending moment $M$ will create normal stress $\sigma$ that acts in the $x$ direction. The magnitude of ${\sigma }_x$ varies linearly over the depth of the shape (i.e., in the $y$ direction). $B$ is above the centroidal axis and the bending moment is positive; therefore, the normal stress ${\sigma }_x$ at $B$ will be compression.

To calculate ${\tau }_{xy}$ and ${\sigma }_x$ at $B$, we will first need to compute the moment of inertia $I$ and the moment of area $Q$.