Circles

What is a Circle?

What exactly is a circle? Learn the answer in this tutorial. You can also see the equation for a circle that's on the coordinate plane!
How Does the Equation For a Circle Relate to Its Graph?

The standard form equation for a circle can tell you quite a bit about the graph of that circle! Learn more about it with this tutorial.
What is a Tangent Line to a Circle?

What does it mean when a line is tangent to a circle? In this tutorial, you'll learn what a line needs to do to be a tangent line to a circle.