Selected Problems and Theorems of Elementary Mathematics . Geometry, Stereometry" by D. About. Shklyarsky, N. N. Chentsova and I. M. Jagloma is a unique textbook that will be a real discovery for all who seek to understand the basics of mathematics more deeply. This edition is not just a collection of problems and theorems, but a whole world in which the reader will be able to plunge into the fascinating and sometimes mysterious aspects of geometry and stereometry. The book contains carefully selected tasks covering a wide range of topics: from simple figures to complex spatial objects. Each section is permeated with the spirit of research approach, which makes the study of mathematics not only useful, but also interesting. The authors, having rich experience in teaching and scientific activities, offer the reader not just solutions, but a whole methodology that allows them to independently come to the necessary conclusions. This is especially important for students, schoolchildren and anyone who is ready to delve deeper into the study of mathematics .. Who can like this book? First of all, it will be useful for high school students and students studying mathematics at a higher level. However, interest in it can be shown by teachers who are looking for new approaches to explaining complex topics, as well as lovers of mathematics who want to expand their knowledge and skills. If you have ever wondered how to better understand geometric shapes or how to apply theorems to practical problems, then this publication will be your reliable assistant. The topics raised in the book go beyond the simple study of formulas and theorems. The authors focus on logical thinking, develop the ability to analyze and synthesize information. The reader will be able not only to solve problems, but also to understand how and why certain mathematical principles work. This is especially important in light of current educational trends, where the emphasis is on critical thinking and practical application of knowledge. The style of the authors is clear and accessible. Shklyarsky, Chentsov and Jagl are known for their scientific works and textbooks, which have already managed to gain confidence among students and teachers. Their previous works, such as “Elements of Mathematical Analysis” and “Mathematics for All”, were also noted for their high level of presentation and practical orientation. In Selected Problems and Theorems, they continue this tradition by offering the reader not only theoretical knowledge but also practical skills. Selected Problems and Theorems of Elementary Mathematics . Geometry, Stereometry” will be an excellent addition to the library of anyone interested in mathematics. It will not only help to prepare for exams and control, but also open new horizons in understanding the world of numbers and figures. If you are looking for a high-quality guide to geometry and stereometry, which will be not only informative, but also inspiring, then this publication will be your faithful companion in a fascinating journey through the world of mathematics.