The   DinaMath   series of text books was designed to respond to the failings of the     modern   American   math   curriculum   and   to     provide   parents with a supplement     (or a replacement)   to   ensure   that   their   children   learn   basic   mathematics   well     enough   to   succeed in algebra,   trigonometry, and calculus.   A good   knowledge of     arithmetic is essential for these advanced subjects; also,   arithmetic is the part   of math     that is most useful in everyday life.   Clear, coherent   explanations,   plentiful   examples     and practice   problems,   and amusing   pictures   make these books useful and fun for     students.         The fourth book in the series,   "Equations in Geometry", finishes off the pre-Algebra     part of the curriculum and prepares the student for geometry as well.   The book covers     basic geometric concepts, such as   lines,   planes, points,   angles, and rays; after those     basics, it proceeds   to problems   involving   the areas,   volumes,   and angles of plane     figures, and   shows how to   use equations   to solve such problems. The Pythagorean     Theorem is introduced as well. The   book also   contains a chapter on probability and     basic   combinatorics,   and a chapter   on graphs   and   pie charts, to help the student     prepare for standardized tests that cover these subjects.         The book   consists   of two   parts: a   Textbook and a   Workbook. The textbook     contains   explanations,  examples, and a few practice problems for   each lesson. The     workbook   contains problem   sets to   accompany each lesson and answers to all the     problems.