5.1a Circles
5.1.1 Parts of a Circle
1. A circle is set of points in a plane equidistant from a fixed point.
2. Parts of a circle:
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2017/07/Picture28-2-1024x648.png)
(a) The centre, O, of a circle is a fixed point which is equidistant from all points on the circle.
(b)
A sector is the region enclosed by two radii and an arc.
A sector is the region enclosed by two radii and an arc.
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2015/11/Picture25-300x235.png)
(c)
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2015/11/Picture26.png)
An arc is a part of the circumference of a circle.
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2015/11/Picture26.png)
An arc is a part of the circumference of a circle.
(d)
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2015/11/Picture27-300x236.png)
A segment is an area enclosed by an arc and a chord.
![](http://pt3mathematics.blog.onlinetuition.com.my/wp-content/uploads/sites/6/2015/11/Picture27-300x236.png)
A segment is an area enclosed by an arc and a chord.