[SOLVED] Line integral, Cauchy's integral formula

Let be the frontier of the square whose sides are the lines and . (orientation is positive)

Calculate the following integral using Cauchy's integral formula for a function or its derivative.

.

My attempt : I find confusing the "using Cauchy's integral formula for a function or its derivative.", I don't really know what they mean by that.

So Cauchy's formula is .

Looking at the integrand of the integral, I see that it is not defined for . Does that mean that is not analytic in this point?

I believe the integral should equals , I don't really know why.

I need help, I find all this new theory somewhat hard to grasp due to the amount of it.

(Bow)