Inscribed angle
Overview
Important
An inscribed angle in a circle is an angle whose vertex lies on the circle and whose sides are chords of the circle. The angle subtends an arc, which is the part of the circle between the two points where the chords meet the circle.
Important properties
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The measure of an inscribed angle is half the measure of the central angle that subtends the same arc.
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All inscribed angles that subtend the same arc are equal.
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An inscribed angle that subtends a semicircle (diameter) is a right angle (90°).
Deeper topics