1. A long duct has the cross-section of an equilateral triangle with side lengths L = 1 m. Surface 1 is a diffuse reflector to which an external heat flux at the rate of Q' = 1 supplied. Surfaces 2 and 3 are isothermal at T, = 1000K and T3 500 K, respectively, and are purely specular reflectors with &, = E, = 1 1kW/m length of duct is Ez = 0.5. (a) Determine the average temperature of Surface 1, and the heat fluxes for Surfaces 2 and 3. (b) How would the results change if Surfaces 2 and 3 were also diffusely reflecting? 60