# Circles

# Topics

#### The Basics of Circles

Mathematicians like to define things before they start talking about them. This is a good idea in other areas of life too. Ever brought a cake pan to a baseball game because you heard there would b...

#### Arcs

Central angles give rise to another concept that we call: the arc. (Not ark, as in Raiders of the Lost Ark.) More like Noah's ark…but only slightly.It's hard to define what arcs are formally. Bow...

#### Chords

Fun activity time! You'll need a hula-hoop and several huge rubber bands big enough to stretch all the way across the hula-hoop. If you don't have those things, that's fine too. You can just imagin...

#### Inscribed Angles

Let's say you're sharing a pizza with three friends. You order from Inconvenient Pizzas, Inc. because their commercials say their prices are "Unbeatably Low!" Two hours later than promised...

#### Tangents and Secants

Lines and circles tend to avoid each other, because they kind of freak each other out. Lines don't care for the weird curviness a circle has, while circles are mystified by the fact that a line goe...

#### Circles on the Coordinate Plane

Let's take a look at (surprise, surprise) a circle.We don't know anything about this circle. Sure, we've spent almost a whole chapter learning about properties of circles in general, but we don't k...