12 Chapter 1, section 1.2. Riccati Equation. subsection 1.2.6-4. Equations with cotangent.

 12.1 problem 38
 12.2 problem 39
 12.3 problem 40
 12.4 problem 41
 12.5 problem 42
 12.6 problem 43
 12.7 problem 44
 12.8 problem 45
 12.9 problem 46