The cross section of a duct is a right triangle as shown in the figure. The sides of this duct are..

The cross section of a duct is a right triangle as shown in
the figure. The sides of this duct are isothermal and are exchanging radiation.
Assuming a nonparticipating medium between the gray surfaces, find the rates of
heat transfer. Data: T1 = 500 K, T2 = 600
K, T3 = 800 K, _1 = 0.625, _2
= 0.4, and _3 = 0.8.