3rd quadrant. Below is a picture that explains what is positive and in what quadrant. I use the term <em>All students take calculus</em>. If you start in the 1st and go through 2nd, 3rd and forth:
A in all stands for All positive
S in students stands for sin and its inverse (csc) is positive.
T in take stands for tan and its inverse (cot) is positive.
C in calculus stands for cos and its inverse (sec) is positive.
Sorry I need to ask more questions
1/4 - 1/2 = -1/4 but 1/2 - 1/4 = 1/4