Complex numbers have applications in many applied sciences. This online text begins with an introduction to trigonometry, which serves as a starting point for additional discussion about complex numbers (also known as imaginary numbers). The drawings and figures are the only notable downside to this excellent resource, because many of them are somewhat crude; however, they are still fairly easy to...

High school and college students are the target audience of this outstanding math site. The main topics addressed in the nine essays are trigonometry, algebra, and basic calculus. The author does a good job of introducing new concepts and working through examples; however, statements are occasionally made without much justification. Students at the intended level probably do not need detailed...