Geometry tips

Last updated: 15 Nov 2008

There is really only one very important tip that I want to give you for geometry, draw your own diagrams. This is especially important with data sufficiency questions since the diagrams provided in the GMAT for these questions can be misleading.

When drawing diagrams the following guidelines are useful.

• In the diagrams in the GMAT everything that looks like a straight line should be considered a straight line and where lines appear to touch they do but the scale of the drawings may not be accurate, i.e. just because two lines look the same length does not mean they are the same length, just because one angle looks larger than another does not mean that it is. Lines which are parallel or perpendicular or the same length will be marked as such on the diagram or described in the accompanying text.
• If you know the lengths of lines or the size of angles try to make the diagram more or less to scale. This should reduce the number of mistakes you make since you can see what is going on more clearly.
• Unless you know lines or angles are definitely equal then draw them as different as you can. This will stop you making wrong assumptions when you are answering the question.

If you are answering questions from a book then you should still draw your own diagram and avoid just adding notes to an existing diagram because in the real test all diagrams will be on a computer screen.

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