New SAT Math Polygons Video


Do you know your SAT polygons?

A quick little formula that will make your life a lot easier in case you come across an SAT problem that asks about polygons is the following:

Total degree measures of a polygon: 180(n – 2), where n = # of sides of the polygon

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Say, you have to find the total degree measure of an octagon (that’s the shape of a stop sign). But no need to stop here! We can just plug in ‘8’ for n and we get:

180(8 – 2) = 180(6) = 1080

Another helpful formula to know is the degree measure of any one side of a congruent polygon. A congruent polygon has equal sides, and therefore equal angles. All you have to do is to take the original formula and divide by ‘n’. This makes sense because you are taking the total degree measure and finding out the measure for any one side. So that’s why we divide the total degrees by the number of sides:

[180(n – 2)]/n

Returning to n = 8, let’s assume the octagon is congruent. What is the measure of any of its sides?

180(6) = 1080/n = 1080/8 = 160

Now you’ve learned two useful formulas dealing with polygons!

Degree measure of sides in a congruent polygon:

[(n – 2)180]/n


  • Chris Lele

    Chris Lele is the Principal Curriculum Manager (and vocabulary wizard) at Magoosh. Chris graduated from UCLA with a BA in Psychology and has 20 years of experience in the test prep industry. He's been quoted as a subject expert in many publications, including US News, GMAC, and Business Because. In his time at Magoosh, Chris has taught countless students how to tackle the GRE, GMAT, SAT, ACT, MCAT (CARS), and LSAT exams with confidence. Some of his students have even gone on to get near-perfect scores. You can find Chris on YouTube, LinkedIn, Twitter and Facebook!

By the way, Magoosh can help you study for both the SAT and ACT exams. Click here to learn more!

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