Special right triangle triangles are used to aid in calculating common trigonometric functions, as below: The 45°–45°–90° triangle, the 30°–60°–90° triangle, and the equilateral/equiangular (60°–60°–60°) triangle are the three Möbius triangles in the plane, meaning that they tessellate the plane via reflections in their sides; see Triangle group. In plane geometry, constructing the diagonal of a square results in a triangle whose three angles are in the ratio 1 : 1 : 2, adding up to 180° or radians. Hence, the angles respectively measure 45° (), 45° (), and 90° (). The sides in this triangle are in the ratio 1 : 1
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,