SAT Video Friday: A Radical Cube

Every now and then you’ll see a cube on the SAT in which a dotted line connects vertices on other ends of the cube. Your job is to find that line. This usually requires that you have to use the Pythagorean theorem twice (talk about cumbersome!). Luckily, I’m here to the rescue. When ever you are dealing with a cube—and notice I said cube and not box—the length of the line connecting two vertices that are at opposite corners of the cube is always s√3, where s is the length of one side of the cube.

Yep, that’s it. Cool little formula to keep in mind. Now the SAT isn’t always going to make such questions a cakewalk. So keeping in line with that devious spirit, I’ve crafted a question involving this concept.

Watch the video below and see if you are able to get the right answer!

If you have any questions for me, feel free to leave them in the comment box below! 🙂


  • 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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