Since I'm homeschooling my high school sophomore this year, I've been spending time looking at math books. "Painless Geometry" seemed like a good bet. Profusely illustrated (albeit with silly monkey pictures) and written in plain English, it looked like just what we'd want.That's until I started actually using the book. First of all, who ever heard of a 300-page reference book with only three pages of index? How are you supposed to find things that way? It's missing things like the base of a triangle (the index has neither "base" nor "triangle:base") and how to label an angle. The information's in the book, but you certainly can't find it using the index. Not only that, but the pages aren't labeled like a normal book, with the name and number of the chapter at the top or bottom of each page. You can't find your place in a book that way!
There's little depth to the book. There are experiments with pencil and paper, but no real-world examples of where you'd use geometry. Area is calculated in "square units" with no discussion of real units of measure. Pi is introduced with a single paragraph. No explanation is given of its rich history, how it's calculated, or applicability throughout mathematics.
The oversimplifications in this book may make life difficult later. The book states that all angles are measured in degrees, and the degrees symbol is generally omitted. Whatever happened to radians? In one of the problems, she asks for the area of a circle with diameter of ten. The correct answer is 100 times pi. The book states the answer as 314. That's an approximation, not an answer!
Then we started finding the mistakes. Typos like "Computer the area of a circle" (page 184) I can live with. It's hard core mistakes like these I can't tolerate:
The reader is asked to identify what type of triangle has angles of 120, 35, and 35 degrees (page 101). The answer says it's isosceles and obtuse. In reality, it's not a triangle at all, as the angles don't add up to 180 degrees!
How's this for a statement of the Side-Angle-Side postulate (page 126)? "If two sides and the included angle of one triangle are congruent to two triangles and the included angle of a second triangle, then the triangles are congruent." Huh?
There's a "super brain tickler" on page 163 which indicates, according to the answers in the book, that for squares, rhombuses, rectangles, and parallelograms, all four sides are parallel! No. Four parallel line segments wouldn't ever meet. Those four shapes have two sets of parallel sides, not one set of four parallel sides!
.... That tends to leave us with drek like "Painless Geometry."
All in all, I found this book to be poorly proofread, ridded with errors, badly indexed, oversimplified, and disconnected from the real world. It may be good as an adjunct for a student having trouble with a real geometry book, but only if there's someone around to explain what "Painless Geometry" omits or misstates.
