- Centre: 'O' is a centre of the circle i.e. fixed point in the circle.
- Radius: OM is a radius of circle i.e.from centre to the boundary of circle.
- Diameter: Double of radius. In figure, XY is a diameter.
- Circumference: 2`pi`r i.e. distance around the circle.
- Secant: A line which intersect the circle at two points. In figure, line PQ intersect circle at AB, So PQ is a secant.
- Tangent: Any line which touches the circle at only one point is tangent of circle. TU is a tangent of circle.
- Chord: Line whose end points touches the circle . RS is a chord of circle.
- Segment: Chord divides the circle into two parts. one major and other minor. Both parts are known as Segments. In figure, yellow region is a minor segment.
Important Results of Circles
Area of Circle
Angles of same segment
- Angles subtended by same segments are always equal. In figure, angle P and Q are equal, as they are subtended by same segment.
- Angle subtended by segment at the centre is twice the angle subtended at the boundary Angle O = 2 angle P = 2 angle Q.
Above figure shows that, If OC is a perpendicular to AB, C will be the mid-point of AB
i.e. AC = CB and vice-versa.
Alternate segment theorem
I hope you understand the above important results. Will soon update more articles on Geometry. Thanks for visiting.
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