Geometry Rules

So here I am, 4 days after I first said I'd blog about studying for the new GMAT.

In that time, I've worked some 40 hours already (who said one has to have a life, anyway?), have cleaned my home (okay, I tidied up a bit), have done some grocery shopping (one does have to eat).

What I haven't done is come up with a schedule.

I have, however, started brushing up on the Quantitative Analysis section of the GMAT - more specifically, the Geometry bit, as that's where I know I can easily gain a few points, given that that used to be one of my strengths in Math. (Did you know that most kids in CommonWealth countries think of that subject as Maths, rather than Math?)

What I don't know, apparently, takes several good-sized books to cover. There is a whole industry of training centres and publishers who focus on exactly the sort of test-taker that I am, someone who's been out of touch with the academic world for a while (a long while in my case), and who needs a very, very thorough refresher course.

So, what do I know?

As I said, I know that a right angled triangle is the basis of Pythagoras' famed theorem:

And I know a few more details about circle and circumferences and triangles.

There are some amazing things that I am pretty certain I never learned in school in India: little short-cuts that save a whole lot of manual derivation!

For example, did you know that the Pythagorean theorem above forms the basis of a whole lot of very useful shortcuts to calculate various facts about a variety of shapes based on rectangles and squares?

You can, obviously calculate the length of the diagonal of a rectangle or square if you know the lengths of two adjacent sides, and so on. However, I hadn't ever realised that the length of the main diagonal of a cube (all sides of a cube are the same length) works out to the length of its side multiplied by the square root of three! Or that the diagonal of a simple square is the square root of 2 multiplied by the length of its side. And so many more.

Pick up a good high school math book - or even just search for "high school math" online, and you'll find a plethora of such examples.

Why are these formulas important?

Because, when you have a TON of stuff to re-learn, the biggest bang for the buck is going to be whatever is simple and helps you save time while writing the test.

Think about it, which would you rather spend time on? Figuring out diagonals of obscure polygons, or actually paying attention to those twisted little data sufficiency problems which seem so straightforward at first glance?

I'm voting data sufficiency ... I tend to jump to the most glaringly obvious (and usually wrong) answer

So, just for this week, I'm busy practising triangles and squares and rectangles and various polygons based on those.

Hopefully, I'll remember those on test day ...