I'm working on a problem that has contour integrals and checked the answers my professor provided with a solution sheet, however there's a part in the solution sheet I don't understand.

This is the question given:

http://img29.imageshack.us/img29/9885/problem1o.png

This is the solution:

http://img687.imageshack.us/img687/5355/solutionk.png

And this is the part I don't understand from this solution:

http://img97.imageshack.us/img97/903/confuzzle.png

Thanks in advance for any help.