Segment of a Circle
Definition: The region between a
of a circle and its associated
Try this Drag one of the orange dots that define the endpoints of the blue arc.
The yellow area is a segment of the circle C.
The chord AB
in the figure above defines one side of the segment.
As you drag the points you will notice that the segment is always the smaller part of the circle.
This is a definition of a segment.
Its Central Angle is always less than 180°
In fact, if the chord divides the circle exactly in half (becoming a diameter) neither of the two halves are segments.
They are semicircles. If you careful with the mouse, you can create this situation in the figure above. Move A or B
so that the line AB passes through the center of the circle. No segment is then present.
A segment is defined by the arc and
that form its outer boundary.
See Arc Definition and
Chord Definition for more information.
The key properties a segment inherits from them are shown below. In the figure above click on "show details" to see these items.
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Other circle topics
Equations of a circle
Angles in a circle
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