Cambridge IGCSE Additional Mathematics · Syllabus 0606 · Circular Measure
Circular Segment
What is Circular Segment?
The region of a circle cut off by a chord, bounded by that chord and one of the two arcs it separates. Its area is found by removing from the sector the triangle formed by the two radii and the chord, giving one half r squared multiplied by the quantity theta minus sine theta, where theta is the central angle in radians and the sine is evaluated on that same radian value. No radius lies on a segment's boundary, so the perimeter of a segment is the arc plus the chord, the chord itself being twice r times the sine of half the angle.
This definition is part of the Circular Measure chapter in Cambridge IGCSE Additional Mathematics.