Halve an Intercepted Arc for an Inscribed Angle
An inscribed angle has its vertex on the circle.
About 20 minutes, plus any extended practice
Open lesson 1Geometry: Circle Theorems, Arcs, and Sectors
Circle angle theorems distinguish central, inscribed and tangent configurations. A sector or arc occupies a stated fraction of the whole circle, but its area and length use different whole-circle measures and units.
Before you begin
- Identify radius, arc and circumference; use fractions of totals; distinguish degrees from length.
Choose by skill rather than age alone. Read with an adult when useful, revisit a lesson, or explore another grade.
Follow the lesson sequence
Use the Right Angle at Tangency
A tangent meets a circle at one point, and the radius to that point is perpendicular to the tangent.
About 20 minutes, plus any extended practice
Open lesson 2Take a Fraction of the Circumference
A degree-measured arc covers its angle divided by 360 of the full circumference.
About 20 minutes, plus any extended practice
Open lesson 3Take a Fraction of the Circle Area
A sector bounded by two radii occupies a fraction of the full disk.
About 20 minutes, plus any extended practice
Open lesson 4Review and transfer
After the lessons, try 4 new review cases and a practical task. Each answer has an explanation and a link back to the related lesson.
Open the unit reviewGuest answers are temporary. Keep your own paper or document; this unit does not certify completion or record a school grade.
Topic references
- California CCSS mathematics topic reference: topic reference — Geometry: Circle Theorems, Arcs, and Sectors
These references informed the topic selection. They do not certify complete standards alignment.