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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:

We then defined a chord:

We then moved to a diameter:

We also discussed inscribed angles and arcs:

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

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

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