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Lesson 9-2 - Introduction to Circles

Today, we defined a whole bunch of things related to circles. We started by recalling the formulas for area and circumference of circles:

Area & Circumference of a Circle

We then defined a chord:

Definition of a Chord

We then moved to a diameter:

Definition of a Diameter

We also discussed inscribed angles and arcs:

Definition of Inscribe Angle


Definition of an Arc


Definition of a Semicircle


Definition of Minor & Major Arcs


Arc Measure vs. Arc Length

We then talked about the measure of inscribed angles.'s always half of the measure of the arc it intercepts:

Measure of an Inscribed Angle

And wrapped up by discussing sectors and how to find their areas:

Definition of a Sector


Sector Area Formula

This was an example of calculating the area of a given sector:

Example of Calculating Sector Area

Other Links
Class Notes
Lesson 9-1
Lesson 9-2
Lesson 9-3
Lesson 9-4
Quiz Topics
Lesson 9-5
Lesson 9-6
Lesson 9-7
Lesson 9-8
Lesson 9-9
Lesson 9-10
Test Topics
Trig Table
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