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Triangle ABC is inscribed in a circle with center O. Angle ABC = 66 degrees. Since AB and BC are chords, and the angle subtended by arc AC at B is 66 degrees, the angle subtended by arc AC at the center O is 2 * 66 = 132 degrees. Triangle AOC is an isosceles triangle with OA = OC (radii). Angle OAC = Angle OCA = (180 - 132) / 2 = 48 / 2 = 24 degrees. The length x represents the chord AB. Without more information or angles related to AB, x cannot be determined.