Inscribed angle "V" and whose sides pass through points "A" and "B". Draw line "OA". Angle "BOA" is a central angle; call it "θ". Lines "OV" and "OA" are both radii of the circle, so they have equal lengths. Therefore, triangle "VOA" is isosceles, so angle "BVA" (the inscribed angle) and angle "VAO" are equal; let each of them be denoted as "ψ". Angles "BOA" and "AOV" are supplementary. They add up to 180°, since line "VB" passing through "O" is a straight line. Therefore, angle "AOV" measures 180° − "θ". It is known that the three angles of a triangle add
Angle C, and ∠CAB to the anticlockwise (positive) angle from C to B. The names, intervals, and measured units are shown in a table below: When two straight lines intersect at a point, four angles are formed. Pairwise these angles are named according to their location relative to each other. A transversal is a line that intersects a pair of (often parallel) lines and is associated with "alternate interior angles", "corresponding angles", "interior angles", and "exterior angles". There are three special angle pairs which involve the summation of angles: The size of a geometric angle is usually characterized by the magnitude