Answer:
b) Negative one-half
Explanation:
according to the equation:

This value is located in the IV quadrant, however we can add 180 degrees and still remain the same value

Now, "b" is located in the II quadrant, so:

I guess you want to get the result with calculator, so we will use an identity to be able to enter this value into the calculator.

Therefore, we have found the solution to the exercise.
