 | A minor arc is an arc of a circle with a measure of less than or equal to 180 degrees. | | |
|  | A major arc is an arc of a circle with a measure of greater than or equal to 180 degrees | | |
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 | The arbelos or "cobbler's knife" is a figure made up from 3 semi circles. | | |
|  | Arc length is a fraction of the circumference. | | |
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 | The measure of the angle made by intersecting chords is equal to the average of the measures of the subtended arcs. | | |
|  | If secants intersect outside the circle, the angle between the secants is equal to the difference of the measures of the subtended arcs divided by two. | | |
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 | Any point on the unit circle has the coordinates (cos(θ), sin(θ)). | | |
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