# GMAT Skills: Understanding Circles

January 28, 2013

General

It’s work developing your GMAT skills. We have to always remember that the GMAT is not a typical test–it isn’t testing your knowledge of a subject as much as it’s testing your ability to take the GMAT.

Of course this doesn’t mean that we don’t have to refresh our memory of, or even relearn, topics we may not have thought about in a while. Because circle problems are one of the most common types of geometry questions, they are up there among the important GMAT skills you need to develop.

So, first we need to refresh ourselves on what, exactly,  a circle is. Beat the GMAT tells us:

A circle is defined as a collection of all of the points that are equidistant from a center point. This distance is defined as the radius of the circle and the diameter is defined as twice the radius. For this reason, the radius of a circle is the key measurement when working with circles. On circle problems, knowing or solving for the radius will almost always be essential.

Then what? We also need to understand , the ratio between the the circumference and diameter of a circle, and how to figure circumference and area (remember and ?). Among these other GMAT skills to develop, “you must also be prepared to calculate sector areas and arc lengths. Sector area is the area of a slice of the circle, and arc length is the distance between two points along the circle.”

There are many useful sources to help you develop these geometry GMAT skills. There are books, classes, posts and video that gives you many examples and tips on circles. Also, remember that “if you have any ONE of the following: Area, Circumference, Radius, or Diameter, you can solve for all of the others!”

All the top business schools in Virginia will be looking at your scores only in comparison to others’ scores. By keeping these rules in mind, you’ll be able to tackle these circle problems much more quickly and be able to devote quality time to the more complicated, advanced questions.