This lesson covers vocabulary for one of geometry’s key 2D shapes: circles.
- center (UK "centre")
- circumference
- diameter
- chord
- radius / radii
- bisect
- pi
- arc
- sector
- segment
- major segment
- minor segment
- secant
- tangent
- inscribed angle
- central angle
Circle
Examine the image below:
A circle has a variety of parts:
- Center: The middle of the circle is called the center. The line of a circle is always equidistant from the center (if some parts are closer or further to the center, it becomes an oval).
- Circumference:The circumference is the measure for the distance around the circle (in other words, it's the line of the circle).
- Diameter: The diameter is the line that bisects the circle. This means it divides the circle into two equal parts with a line through the the center. Any straight line that has both endpoints on the circle is called a chord. A diameter is a kind of chord. It is the longest chord of any circle.
- Radius: The distance from the center to the outside of the circle is called the radius.
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