Inscribed angle
SAT glossary · Math
Definition
An angle with its vertex on the circle; it is half its intercepted arc. The named distractors treat it as a central angle (forgetting the halving) or double instead of halve — keep the direction straight by remembering the vertex further from the arc sees it smaller.
Inscribed angle in plain English
An inscribed angle is an angle whose corner point (vertex) sits right ON the circle itself, with its two sides stretching out as chords to two other points on the circle. The key rule: an inscribed angle always measures exactly HALF of the arc it 'cuts off' (the arc between where its two sides land on the circle). The traps here go both directions: some wrong answers accidentally treat the angle like a CENTRAL angle (one with its vertex at the circle's center, which equals the full arc, no halving needed), and others double the arc instead of halving it. A helpful way to keep the direction straight: the further the vertex sits from the arc it's looking at, the smaller the angle appears — matching the fact that it's cut in half.
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