Area of Circles & Sectors

Is Pi really 22-7?

Rumor or innuendo? Fact or fiction? Truth or dare? Rationally repeating decimal or... I could go on but won't. If your teacher or friend has told you that pi is 22/7, this video may be for you. If this is the first you're hearing that pi is 22/7, no need to watch.

Basic Circle Area Problems

This video shows you how to work the most common types of circle area problems, and tricks for avoiding errors. The easier ones are when the problem provides a radius and asks for area. In the harder area problems you are given something other than radius, such as circumference or diameter, or you are asked to work backwards from area to find radius or diameter.

Areas of Circle Sectors

Even for sectors with crazy angle measures, I find that always thinking of sectors as slices of pizza is really the best way to make sene of what is otherwise a confusing topic.

Sector Area Word Problems

By popular demand, a separate video of word problems! Naturally there are a few pizza problems (we are talking about sectors, after all), but we'll also get into percentages and pie charts, which seem to be the only place you come across sectors after geometry class is over (other than when you're eating pizza).

Difficult Circular Region Area Problems (SAT)

Circles with other circles inside of them, "shaded regions", circles inscribed in squares, triangles inscribed in circles... If you're only going to watch one video about circle areas, this is the one becuase these problems are the type you'll see on standardized tests like the SAT.

Circle Area Word Problems

How much of a pizza is crust? How much sheetmetal is used in the Hollywood sign? Are circular horse arenas more efficient uses of fencing than square ones? This video answers all these questions, and so many more.