A solar collector consists of a long duct through which air is blown; its cross section forms an equilateral triangle 1 m on a side. One side consists of a glass cover of emissivity 0.9, while the other two sides are absorber plates with 1.0. Illustration shows a equilateral triangle, with one side protected by a glass cover and the other two sides protected by absorber plates. During operation the surface temperatures are known to be 25°C, 60°C, and 80°C. What is the net rate at which radiation is transferred to the cover due to exchange with the absorber plates, in W/m?