Geometric Inequalities 
Nicholas D. Kazarinoff
Mathematical Association of America (MAA)
Anybody who liked his first geometry course will enjoy the simply stated geometric problems about maximum and minimum lenghs and areas in this book. Many of these already fascinated the greeks, for example the problem of of enclosing the largest possible area by a fence of given length, and some were solved long ago; but others remain unsolved even today. Some of the solutions of the problems posed in this book, for example the problem of inscribing a triangle of smallest perimeter into a given triangle, were supplied by world famous mathemaicians, others by high school students.