This is a challenging problem-solving book in Euclidean geometry, assuming nothing of the reader other than a good deal of courage.

Topics covered included cyclic quadrilaterals, power of a point, homothety, triangle centers; along the way the reader will meet such classical gems as the nine-point circle, the Simson line, the symmedian and the mixtilinear incircle, as well as the theorems of Euler, Ceva, Menelaus, and Pascal. Another part is dedicated to the use of complex numbers and barycentric coordinates, granting the reader both a traditional and computational viewpoint of the material. The final part consists of some more advanced topics, such as inversion in the plane, the cross ratio and projective transformations, and the theory of the complete quadrilateral. The exposition is friendly and relaxed, and accompanied by over 300 beautifully drawn figures.

The emphasis of this book is placed squarely on the problems. Each chapter contains carefully chosen worked examples, which explain not only the solutions to the problems but also describe in close detail how one would invent the solution to begin with. The text contains as selection of 300 practice problems of varying difficulty from contests around the world, with extensive hints and selected solutions.

This book is especially suitable for students preparing for national or international mathematical olympiads, or for teachers looking for a text for an honor class.

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### About the Author

Evan Chen is a past contest enthusiast hailing from Fremont, CA. In 2014 he was a winner of the USA Mathematical Olympiad, and earned a gold medal at that year’s International Mathematical Olympiad. He is currently an undergraduate studying in Cambridge, Massachusetts, where he serves as problem czar for the Harvard-MIT Math Tournament.