Inscribed angle its intersection points equals half of the central angle subtended by the chord. See also Tangent lines to circles. The inscribed angle theorem is used in many proofs of elementary Euclidean geometry of the plane. A special case of the theorem is Thales' theorem, which states that the angle subtended by a diameter is always 90°, i.e., a right angle. As a consequence of the theorem, opposite angles of cyclic quadrilaterals sum to 180°; conversely, any quadrilateral for which this is true can be inscribed in a circle. As another example, the inscribed angle theorem is the basis for several
Allied Masonic Degrees with the presiding officer being denominated 'Sovereign Master." The Councils are given wide discretion as to choose how frequently they meet and what programs to pursue. Generally speaking, Councils study or discuss Freemasonry in some way at each meeting. The Grand Council has created some internal honors, the most notable being "Knight Grand Cross". The degrees conferred in the United States are: In Canada, the degrees conferred are: Optional degrees are: Royal Order of the Red Branch of Eri: "Fun" degrees: (given at the Annual Assembly) Allied Masonic Degrees The Allied Masonic Degrees (AMD) are a series of Masonic degrees