This 3-part treatment begins with the mechanics of writing proofs, proceeds to considerations of the area and circumference of circles, and concludes with examinations of complex numbers and their application, via De Moivre's theorem, to real numbers. "I recommend this as a textbook or supplemental textbook." — Brian Rogers, The Mathematical Association of America. 1998 edition. Reprint of the Prentice Hall, Inc., Upper Saddle River, New Jersey, 1998 edition.
Here's a sample of other books in this Dover category
Concepts of Modern Mathematics by Ian Stewart In this charming volume, a noted English mathematician uses humor and anecdote to illuminate the concepts of groups, sets, subsets, topology, Boolean algebra, and other mathematical subjects. 200 illustrations.
Mathematics: Its Content, Methods and Meaning by A. D. Aleksandrov, A. N. Kolmogorov, M. A. Lavrent’ev Major survey offers comprehensive, coherent discussions of analytic geometry, algebra, differential equations, calculus of variations, functions of a complex variable, prime numbers, linear and non-Euclidean geometry, topology, functional analysis, more. 1963 edition.
