Consider inclined surfaces $(A_1,A_2)$ of width $20$ mm maintained at uniform temperatures of$,T_1=1200$ K and $T_2=950K.($a$)$ Determine the view factors $F_{11},F_{12},F_{13},F_{21},F_{22}$ and $F_{23}(10$ points$)($b$)$ Determine the net radiation exchange between the surfaces $(A_1,A_2)(5$ points$).$ After calculating the net radiation exchange in $($b$),$ consider the configuration when a black surface $(A_3),$ whose back side is insulated, is positioned along the dashed line shown. $($c$)$ Calculate the net radiation transfer to surface $A_2$ when the temperature of the insulated surface $A_3$ is $T_3=1096K(5$ points$).$