A straight fin having a triangular profile has a length of 5 cm and a thickness of 4 mm and is constructed of a material having k = 23 W/m ∙ ºC. The fin is exposed to surroundings with a convection coefficient of 20W/m2 ∙ ºC and a temperature of 40ºC. The base of the fin is maintained at 200ºC. Calculate the heat lost per unit depth of fin.