23. Complex Numbers
A brief history of complex numbers is given from antiquity through Euler’s identity. The need for complex numbers is mentioned. Basic operations of the imaginary number ‘j’ are shown. The rectangular form of complex numbers is introduced and related graphically to the polar form of the complex number. Conversion between rectangular and polar forms is demonstrated. The need for both expressions of a complex number is discussed. Operations involving complex numbers shown include addition, subtraction, multiplication, division, and complex conjugates. Multiplication and division are done in both rectangular and polar form. Complex conjugates are discussed in both rectangular and polar form.