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
Poem of the Right Angle Poem of the Right Angle The Poem of the Right Angle ("Le Poeme de l'Angle Droit") is a series of 19 paintings and corresponding writings composed by the influential Swiss-French architect Le Corbusier between 1947 and 1953. Aside from his seminal manifesto "Toward an Architecture", "The Poem of the Right Angle" is considered to be his most lucid synthesis of personal maxims. "The Poem of the Right Angle" was composed over a period of seven years, from 1947-1953. The paintings are arranged symmetrically in seven rows, or "zones" and read across, in order, 5, 3, 5, 1, 3, 1, 1