AI Tutor
Imagine slicing a round pizza. If you cut from the center straight out to the edge, you get a classic triangle-shaped slice β€” but what happens if you cut straight across the crust instead?
Those two cuts create completely different shapes inside a circle, and each one has its own special name in geometry.
Before looking inside the circle, what do we call just a piece of the outside edge?

Arcs: Along the Edge

An arc is any curved portion along the outer boundary (the circumference) of a circle.
If an arc covers less than half the circle (under 180∘180^\circ), it is a minor arc. If it covers more than half (over 180∘180^\circ), it is a major arc.
When an arc measures exactly half the circle (180∘180^\circ), we call it a semicircle.
Arcs are just curved lines along the rim β€” but what shape do you get when you color in the space all the way to the center?

Sectors: Slices from the Center

A sector is a pie-shaped region of a circle bounded by two radii and the arc connecting them.
Think of a radius as a spoke on a bicycle wheel running from the center point to the rim. Because both lines meet right at the center point, every sector looks like a wedge or a slice of pie.