Geometry – Angles in Circles

In this lesson we will learn:
- Central angles and arcs: As you'll see, there are 360 degrees in every circle
- Inscribed angles: Discover how inscribed angles are related to central angles!
- Inscribing the diameter: Prove that inscribed angles drawn to diameters are right
- Arc length: Finding a formula for the length of any arc
- Sector Area: How to find the area of any slice of a circle
Central angle is an angle between two radii in a circle.
Arc is part of a circle’s circumference between two points.
An arc’s measure is the measure of its central angle.
Circle is a curve made up of all the points that are the same distance from the center.
Radius are any line segment between a circle and its center.
Diameter is any chord that passes through the center.
Circumference is the distance around a circle.
An inscribed angle has a vertex on the circumference.
For any arc, every inscribed angle is exactly half of the central angle.
Any inscribed angle to a diameter is always a right angle.
Sector is a region of a circle between two radii.

Geometry – Angles in Circles - Central Angles and Arcs | Inscribed Angles: 

Geometry – Angles in Circles - Inscribing the diameter | Arc length: 

Geometry – Angles in Circles - Sector Area: