a).

From the given data angle =.

To find positive angle, subtract to obtain a co - terminal angle

- =.

To find negative angle, add to obtain a co - terminal angle

+ =.

The solution is positive angle is and negative angle is .

b).

From the given data angle =.

To find positive angle, subtract to obtain a co - terminal angle

- =.

  To find negative angle, add to obtain a co - terminal angle

+ =.

The positive angle is and the negative angle is .