Entertaining geometry in the free air

At twelve, Albert Einstein called the geometry textbook his "sacred book". And the great scientist said: "The first foundations of geometry should not be laid in the school room, but in the free air."
The famous popularizer of science Yakov Isidorovich Perelman did so: he brought geometry from school for a walk and made it truly entertaining science.
How to determine the height of a tree using a notebook?
Is it possible to weigh a growing tree?
How to measure the width of the river without crossing it?
How stronger is the ant?
Where is the horizon further - on Earth, Moon or Jupiter?
How to become a Robinson? ..
on these and many other unexpected questions you can find an answer using entertaining geometry. The best guide in the world of entertaining sciences, a patient guide and a wonderful storyteller - Yakov Perelman will help to understand all its wisdom. He will even be able to turn the enemies of geometry into her friends!
Continuation of the trip - in the second part: "Entertaining geometry between business and a joke".
For children of secondary school age