A beam having the cross section shown is subjected to a vertical shear $V.$ Determine $($a$)$ the horizontal line along which the shearing stress is maximum, $($b$)$ the constant $k$ in the following

expression for the maximum shearing stress ${}_{\text{m}\text{a}\text{x}}=k\frac{V}{A}$ where $A$ is the cross$-$sectional area of the beam. For Canvas grading purposes, submit your answer of the constant $k.$