The wing of airplane is approximately a rectangular shape with a wingspan $($the length perpendicular to the flow direction$)$ of $17\mathrm{.}5$ m and a chord $($the length parallel to the flow direction$)$ of $4$ m$.$ The airplane is flying at standard sea level with a velocity of $300$ m$/$s$.$ If the flow is considered to be completely laminar, calculate the boundary layer thickness at the trailing edge and the total skin friction drag. Assume the wing is approximated by a flat plate.