In this section, we introduce an efficient notation to make it possible to represent
sinusoidal signals as complex numbers, and to eliminate the need for solving differential
equations. The student who needs a brief review of complex algebra will
find a reasonably complete treatment in Appendix A, including solved examples
and Check Your Understanding exercises. For the remainder of the chapter, it will
be assumed that you are familiar with both the rectangular and the polar forms of
complex number coordinates, with the conversion between these two forms, and
with the basic operations of addition, subtraction, multiplication, and division of
complex numbers.