In each of the following cases, define a parametrised curve y : [a, b] → C whose image y* is: (a) The closed semi-circle of radius R in the right half-plane. (b) The equilateral triangle with vertices...

Extracted text: In each of the following cases, define a parametrised curve y : [a, b] → C whose image y* is: (a) The closed semi-circle of radius R in the right half-plane. (b) The equilateral triangle with vertices 1,–1, iv3. (c) The two circles {z € C; |z – 1| = 1}U{z € C; |z+ 1| = 1}. Which of these are contours? Justify your answers.