Complex integration of a function around a triangle.

Question

Please help me how to solve this problem. I have no idea how to initiate the solution.

Answer 1

$\gamma_1: z = t\\ \gamma_2: z = a + ti\\ \gamma_3: z = a - t + (a-t)i$

Take the derivatives to find $dz$ for each contour

$\int_0^a t \ dt + \int_0^a a (i \ dt) + \int_0^a (a-t)(-1-i\ dt)$