In Exercises 1-4, use the given conditions to (a) determine the quadrant in which u / 2 lies, and (b) find the exact value of sin(u / 2), cos(u / 2), and tan(u / 2) using the half-angle formulas.
1. cos u = 7 / 25, 0 < u < π / 2
2. sin u = 5 / 13, π / 2 < u < π
3. tan u = - 5 / 12, 3π / 2 < u < 2π
4. cot u = 3, π < u < 3π / 2