The inscribed angle theorem states that an inscribed angle in a circle is equal to one-half the central angle. An alternative way of stating the theorem is that the central angle is twice the inscribed angle.

Variable | Description |
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The inscribed angle is the angle from a point along the perimeter of the circle to the inscribed arc. | |

The central angle is the angle measurement at the center of the circle to the inscribed arc. | |

The inscribed arc is the distance traveled along the perimeter of the circle formed by the inscribed angle. |

- Derive double angle formulas
- Derive half-angle formulas