This is a $3\mathrm{.}4$m long simply supported timber beam that carries a $42$kN concentrated load midspan. The cross$-$section dimensions at a$-$a section of the beam are shown in Figure $2\mathrm{.}2$b$.$ For the section a$-$a$,$ determine the following:

$($i$)$ The magnitude of horizontal shear stress in the beam at point H

$($ii$)$ The magnitude of horizontal shear stress in the beam at point K