Circle — Basic Definitions
Grade 7 Geometry
What Is a Definition?
A definition is a statement that explains the meaning of a term or concept precisely and completely.
In geometry, you have already encountered definitions of important figures:
- Angle — a figure formed by two rays sharing a common endpoint.
- Isosceles triangle — a triangle with at least two equal sides.
Now we will define another fundamental geometric figure — the circle.
📐 Definition of a Circle
Circle — a geometric figure consisting of all points in a plane that are at a given distance from a given point.
In this definition, two things are specified:
- The given point is called the center of the circle.
- The given distance is called the radius of the circle.
So a circle is the set of all points that are exactly the same distance (the radius) from the center. Points closer to the center are inside the circle; points farther away are outside.
Interactive: Circle with Center O
Interactive visualization — available in the full lesson
Drag point P to change the radius.