Since the vector of the magnetic field in respect to each side of the triangle points in the same direction at the center, I should be able to find the magnetic field generated by one side of the triangle and multiply it by 3. After trying several times, I keep getting

B = 1.5uI/(pi*L), in which u = permeability of of free space...but the actual answer is

B = 4.5uI/(pi*L), which is 3 times greater than my answer. After looking over my work, nothing seems to be wrong...but my answer is down by a factor of 3 from the one I'm supposed to get. What am I doing wrong??