Learn about circles, their properties, equations, and applications through interactive lessons and exercises on Khan Academy.

Review the standard and expanded forms of circle equations, and solve problems concerning them.

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Remember, the circle itself is all of the points that are equal distance from the center. So AB, any line segment, I should say, that connects the center to a point on the circle, we would call a radius.

What is the unit circle definition of the trigonometric functions? The unit circle definition allows us to extend the domain of sine and cosine to all real numbers.

Learn how the number Pi allows us to relate the radius, diameter, and circumference of a circle.

The area of a circle is pi times the radius squared (A = π r²). Learn how to use this formula to find the area of a circle when given the diameter. Created by Sal Khan and Monterey Institute for Technology …

The area of a circle is pi times the radius squared (A = π r²). Learn how to use this formula to find the area of a circle when given the diameter. Created by Sal Khan and Monterey Institute for Technology …

Mar 15, 2021 · Looking for free math worksheets? You’ve found something even better! That’s because Khan Academy has over 100,000 free practice questions. And they’re even better than traditional …

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