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
38 Degrees 38 Degrees 38 Degrees is a British not-for-profit political-activism organisation. It describes itself as "progressive" and claims to "campaign for fairness, defend rights, promote peace, preserve the planet and deepen democracy in the UK". In October 2013, it was reported to claim 1.9 million UK members. 38 Degrees takes its name from "the angle at which snowflakes come together to form an avalanche". The organisation launched on 26 May 2009. The 38 Degrees website states: "38 Degrees was founded by a group of activists and funders concerned about the state of our democracy and determined to try something different. Founders