Discusses the properties and types of triangles, explaining that a triangle is a closed figure with three sides and angles. It categorizes triangles into equilateral, isosceles, scalene, obtuse ...

However, Ted is a bit worried, as he has promised to help Titch to learn about geometry and he is not really sure what that means. Before they set off, Titch teaches Ted about triangles, circles ...

A Sequel to the First Six Books of the Elements of Euclid; containing an Easy Introduction to Modern Geometry (with numerous Examples). By John Casey (Dublin: Hodges, 1886.) ...