In geometry, an inscribed angle is formed when two secant lines of a circle (or, in a degenerate case, when one secant line and one tangent line of that circle) intersect on the circle.
Typically, it is easiest to think of an inscribed angle as being defined by two chords of the circle sharing an endpoint.
The basic properties of inscribed angles are discussed in Book 3, Propositions 20-22 of Euclid's Elements. These are the inscribed angle is half the central angle, inscribed angles on the same arc of a chord are equal and the sum of the two distinct inscribed angles of a chord is 180°.
Famous quotes containing the words inscribed and/or angle:
“And ye shall know the truth, and the truth shall make you free.”
—Bible: New Testament John 8:32.
These words of Jesus are inscribed on the wall of the main lobby at the CIA headquarters, Langley, Virginia.
“From whichever angle one looks at it, the application of racial theories remains a striking proof of the lowered demands of public opinion upon the purity of critical judgment.”
—Johan Huizinga (1872–1945)