Book excerpt: This book contains a reasonable collection of problems on hyperbolas represented by binary quadratic Diophantine equations. From the integer solutions of each of the above equations, the relations among special polygonalnumbers are obtained. The formal prerequisites for the material are minimal. It is hoped that these problems may create an interest in the hearts of researchers and lovers of mathematics who approach it with pure love for its beauty. There is no wonder that binary quadratic Diophantine equations in connection with polygonal numbers are beautiful and tricky enough to keep a mathematician occupied for entire life.