You should really say what your question about the problem is. And providing less blurry snapshots would really help. If the question is 'where did I go wrong' it looks to me like it's at the very end. Try and find it. You have a much clearer view of your work than I do.
Ok.You're right.I will try to fix my fault.But I don't have any idea about b and c? Can you help me for b and c?
c is just two straight line paths. What's a line equation for each part? And if you want a circular path it's probably easiest to use trig functions to describe it. Can you give a parametric form for the circle using cos and sin? BTW I think you are also integrating backward in part a). You want to go from (1,0) to (0,1), not the other way around.