AI Tutor
Imagine riding a giant Ferris wheel: the central axle holds everything in place, the steel spokes keep you steady, and the rim carries you all the way around.
In geometry, a circle is the set of all points in a plane that are the exact same distance from a fixed point called the center.
What are the basic line segments that connect these points?

Radii, Chords, and Diameters

A radius is a line segment connecting the center to any point on the circle, while a chord connects any two points on the circle.
When a chord passes directly through the center, it is called a diameter, which is the longest possible chord in any circle.
Because a diameter consists of two collinear radii joined end-to-end at the center, its length is always twice the radius: d=2rd = 2r.
If a circle has a radius of 7 cm7\text{ cm}, its diameter is 2×7=14 cm2 \times 7 = 14\text{ cm}.
What happens when a straight line keeps going instead of stopping at the circle's edge?

Lines: Secants and Tangents

A secant line is an extended line that intersects a circle at two distinct points, cutting completely through it like an arrow.