| A | B |
|---|
| Diameter | The longest chord of a circle |
| Chord | A line segment joining any two points on the circumference of a circle |
| Semi Circle | Half of a circle |
| Segment | A part cut by a chord of a circle |
| Sector | A part cut by two radii of a circle |
| Radius | The distance between the centre of a circle and a point on its circumference |
| Centre | The point equi-distant from every point on the circumference |
| Pi | The ratio of the circumference and the diameter |
| Circumference | The length of the outline of a circle |
| Concentric Circles | Two or more circles having the same centre |
| Tangent | The line touching a circle at one point |
| Secant | The line intersecting a circle at two points |
| Incircle | A circle touching the sides of a triangle |
| Circumcircle | A circle passing through the vertices of a triangle |
| Excircle | A circle touching the extended sides of a triangle |
| Pi * diameter | Circumference of a circle |
| Pi * radius * radius | Area of a circle |
| Right Angle | Angle in a semi-circle |
| 90 degrees | Angle between the radius and a tangent |
| Two | No. of tangents can be drawn to a circle from a point outside it |
