GMAT Math : Geometry deductions

GMAT math, as part of its geometry questions, may often test you with figures or diagrams

Let’s start with an example:

What is the area of the below quadrilateral?

  1. One of the sides measures 7 cm
  2. One of the sides measures 10 cm

Readers are encouraged take some time to tackle this question.

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The GMAT is a very smart test which loves to trick candidates routinely.

In this chapter we want to highlight the importance of not inferring more than what is given in a GMAT geometry diagram.

Coming to the original question, from the figure it is tempting to establish that the quadrilateral is a rectangle and with both statements put together – we can calculate the area of the rectangle. Just like this :

But what if the quadrilateral is actually like this? 🙂

..or like this? 🙂

We cannot determine the area of such a quadrilateral with the information (only two sides) given. Beware of deducing too much information (relative lengths, angles etc) by how a diagram looks in the GMAT Math section

We go with option (E)