Consider the following grooves, each of width W, that have been machined from a solid block of material. (a) For each case obtain an expression for the view factor of the groove with respect to the surroundings outside the groove. (b) For the V groove, obtain an expression for the view factor F_12, where A_1 and A_2 are opposite surfaces. (c) If H = 2W in the rectangular groove, what is the view factor F_12?