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The Pythagorean Theorem on the GMAT

There’s a reason this is the most famous theorem in mathematics!  This remarkable theorem is one of the most versatile and highly adaptable formulas in existence.  Of course, I’m sure you remember that it says: For any right triangle,


Of course, if any question gives you two sides of a right triangle and asks you to find the third, you will use this formula. Here are a couple problems to show its other guises.



Practice Questions: Using the Pythagorean Theorem


1) In the coordinate plane, point A has coordinates (-2, -1) and point B has coordinates (4, 7). What is the length of segment AB?

    (A) 10
    (B) 10.5
    (C) 12
    (D) 13.675
    (E) 14

2) Paul drove 50 miles north, then changed direction and drove 120 miles east. At the end of this trip, how far was he from his starting point?

    (A) 70 miles
    (B) 110 miles
    (C) 130 miles
    (D) 150 miles
    (E) 170 miles


Answers and Explanations

1) The easiest distances to find in the coordinate plane are the horizontal and vertical lines, so we begin by drawing those.

For the lengths of AC and BC, we can simply count boxes. AC = 6 and BC = 8. These are the two “legs” of a right triangle, and AB is the hypotenuse, so





Answer: A.


2) Essentially, Paul drove along the legs of a big right triangle, and the hypotenuse is how far he is from his starting point.

Therefore, (distance from start)^2=50^2+120^2=2500+14400=16900 right

distance from start =sqrt{16900}=130

Answer: C.

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3 Responses to The Pythagorean Theorem on the GMAT

  1. Sirisha December 2, 2014 at 8:27 am #

    Hi, In the explanation to problem 1 above, you mentioned to simply count the number of boxes to get AC and BC. In the real GMAT, is the co-ordinate plane given in box style? Thank you.

    • Mike MᶜGarry
      Mike December 2, 2014 at 10:13 am #

      Dear Sirisha,
      I’m happy to respond. 🙂 Sometimes the GMAT gives the gridlines and sometimes it doesn’t, but even if you are given no diagram at all, it should not be hard to figure out, say, that from the x-coordinate of A, -2, to the x-coordinate of B, 4, there are 6 units. You shouldn’t need the picture at all to be able to count the number of units along a horizontal or vertical line in the coordinate plane.
      Does this make sense?
      Mike 🙂

    • SSY February 6, 2015 at 6:32 pm #

      yes, sometimes it does and sometimes it doesnt.

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