Euclidean geometry equal (SAS), or two angles and a side equal (ASA) (Book I, propositions 4, 8, and 26). Triangles with three equal angles (AAA) are similar, but not necessarily congruent. Also, triangles with two equal sides and an adjacent angle are not necessarily equal or congruent. The sum of the angles of a triangle is equal to a straight angle (180 degrees). This causes an equilateral triangle to have three interior angles of 60 degrees. Also, it causes every triangle to have at least two acute angles and up to one obtuse or right angle. The celebrated Pythagorean theorem (book I,
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,