3. CT reconstruction (40%) Consider the object shown in the following figure that is an equilateral triangle centered at the origin, each side of which is of length a and one side of which is parallel to the x axis. Suppose the object has constant linear attenuation coefficient and is being imaged in a 1G CT scanner. Assume μ = 1 and a = 6. a (0,0) (a) Calculate a formula for the projection g(1, 60°) and sketch it. (b) What is the backprojection value of (0, a/4) for g(1, 60°) calculated in the above?