I read the first edition and found it excellent. When this 2nd edition was announced, I purchased it feeling it might improve over the first edition. I was correct.
This is an outstanding book for self-study. It is well written in essentially non-technical terms when compared to some other mathematics texts. It can be easily understood, even by those just beginning, or refreshing, their study of trigonometry. It defines terms clearly and understandably, and includes some examples to re-enforce the concepts presented. However, the number of examples provided is relatively sparse, and as is often said mathematics is -not- a spectator sport, it needs to be participated in to develop a meaningful understanding.
The small number of worked examples, the lack of Chapter exercises, and the emphasis on statements made without proof are the text's primary weaknesses. For this reviewer, these deficiencies are compensated for by the presentation's excellence. Because of the lack of proofs, this should be considered an applied, rather than a pure, mathematics text. If you are interested is learning basic trig terminology and gaining a fundamental understanding of how trigonometric problems are solved, this is an excellent book (although, as noted, one with a shortage of solved examples, and thus one requiring a supplemental problem book, such as Kelley's excellent "The Humongous Book of Trigonometry Problems").
However, if you're primarily interested in understanding why certain trigonometric statements are true and how to prove these statements, this book is not a good choice.
This edition modifies, augments, and corrects material from the first edition. As examples, the informative section on "Angles in circles" has been added between the "Chord and Tangent" and "Sectors" sections, retained from the first edition. In addition, the first edition presents an example for finding the area of a sector. In that example, the diameter is incorrectly used in place of the radius in calculations. That error has been corrected here.
This book provides one of the clearest explanations of the six trigonometric functions. It presents these using a broad brush introduction in the first Chapter. It later expands and extends this introduction, using an explanation involving the sides of a right triangle. In a still later section, the trig functions are presented from a somewhat different perspective, based on the coordinates of a circle.
This book's text as well as its equations and graphs display nicely on my Kindle DX. However, many equation displays on my Kindle HDX 7", HDX 8.9", PC and Android Kindle emulators are literally unreadable. Enlarging the font, sadly, only enlarges the text, but not these equations or graphs. The equations are still unreadable.
Later Amazon Kindles appears to have a significant problem in displaying formulas, and this problem now appears pervasive. I am not aware (at the time of this review) of any current comment from Amazon about this issue, or even if they are aware of it and have a "fix" planned.
Perhaps, one of Amazon's team will read this review and comment on this problem, present at the time of this posting. It appears ubiquitous in most Kindle editions of mathematics and science texts targeted for the HDXs and Kindle emulators. I do not have HDs or Paperwhites and so cannot comment on versions for those products; perhaps owners of these products will be kind enough to add comments here.
Until this issue is fixed, I would gently recommend that any Kindle version of a mathematics or science text always be sampled on the target Kindle platform before purchase, and if this cannot be done, unless you are using a Kindle DX, the e-version be skipped in favor of the printed book.
This edition and the Kindle DX version can be highly recommended for applied users, but not for mathematicians, who would likely want a more "proof-oriented" text.
This book deserves five stars for its content.
Perhaps Amazon has implemented a solution to the formula display issue. However, I still found this same "formula" problem present in other Kindle books. If Amazon reads these reviews, may I gently suggest that until this problem is resolved, you consider -not- selling Kindle versions of any book containing formulas. If/when this display problem is fixed, please be kind enough to leave a comment with this review. Since Amazon now has an option for automatic updates available, we should then be able to see the correct display of these formulas on our Kindles and Kindle emulators.
When/if I see Amazon's comment I would be pleased to check my HDX and Kindle emulator versions of this book for the proper formula display, and update this review accordingly. Until then, while this text is highly recommended in its book form, it cannot be recommended of any Kindle HDXs or any versions of Kindle emulator software.