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
Inverted sugar syrup pure sucrose it comes out the other side with a different angle than when it entered; its angle is therefore said to be 'rotated' and how many degrees the angle has changed (the degree of its rotation or its 'optical rotation') is given a letter name, formula_1 (alpha). When the rotation between the angle the light has when it enters and when it exits is in the clockwise direction, the light is said to be 'rotated right' and formula_1 is given to have a "positive" angle like formula_3. When the rotation between the angle the light has when it enters