Triangle their internal angles, measured here in degrees. A triangle that has two angles with the same measure also has two sides with the same length, and therefore it is an isosceles triangle. It follows that in a triangle where all angles have the same measure, all three sides have the same length, and such a triangle is therefore equilateral. Triangles are assumed to be two-dimensional plane figures, unless the context provides otherwise (see Non-planar triangles, below). In rigorous treatments, a triangle is therefore called a "2-simplex" (see also Polytope). Elementary facts about triangles were presented by Euclid in books 1–4
Lectures of the Three Degrees in Craft Masonry Lectures of the Three Degrees in Craft Masonry The Lectures of the Three Degrees in Craft Masonry is a series of manuals on Freemasonry that are arranged in the form of catechisms to be memorized. They cover rituals and symbolism associated with the three degrees of Craft Freemasonry in question and answer form. During the second half of the 19th century, the Lectures gradually ceased to be used regularly in English Lodges. The question and answer procedure was the traditional way in which Freemasons were instructed in Masonic ritual and symbolism before printed ritual books became more widely available. Usually,