# Circles and Tangent Lines

### Popular Tutorials in Circles and Tangent Lines

#### How Do You Determine Whether a Line is Tangent to a Circle?

In this tutorial, you'll see how the Converse of the Pythagorean Theorem is used to figure out if a line is tangent to a circle.

#### 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.

#### How Do You Find the Diameter of a Circle if You Know its Radius?

When you know the radius of a circle, you can find the diameter of that circle with a simple multiplication problem! Follow along with this tutorial to learn how to find the diameter of a circle when you're given the radius.

#### What is a Circle?

Circles are a fundamental part of math! In this tutorial, you'll be introduced to circles and see the different parts of a circle such as the diameter, radius, and chord. Check out this tutorial to learn about circles!