onsider the view factor $F_{14}$ for surfaces $1$ and $4$ of the following geometry. These surfaces are perpendicular but do not share a ommon edge.

Derive an expression for the view factor $F_{14}$ and using this expression, if $L_1=L_2=L_4=1,W=2,$ and $L_3=2,$ determine the value of $F_{14}$