What is REALLY important in Gmat geometry?

Question

Hi everyone,

A quick question here,

What should i study the most from geometry section? There seem to infinite formulas, tricks, polygons, relations between them etc etc etc. I suppose it's not necessary to memorize the dozens of formulas! So what is really important? Can someone pinpoint the relevant topics to study?

Thank you!

OptimusPrepJanielle · Answer

Geometry is a vast section and takes a lot of effort to familiriaze yourself with certain topics.
To start with, you can pay special attention to:

1. Circle and its properties
2. Triangles and their properties
3. Understand the sin, cos and tan rule
4. Squares and rectangles.

You will find that most of the questions come from these topics.

1. Are you following any preparatory course/book?
2. Have you completed the OG questions?
3. Have you taken a full length mock CAT?

Bunuel · Answer

Just to make clear: trigonometry is NOT tested on the GMAT. Each and every GMAT geometry question CAN be solved without trigonometric properties.

ENGRTOMBA2018 · Answer

iliavko , what is your target GMAT quant score/ total score? I ask this as your posts seem to indicate that you dont want to put in the required amount of effort towards your GMAT preparation. We all have certain sections in GMAt that are difficult but make sure that we spend good amount of time in honing our skills in those areas. Just doing the requisite sections (that you can do COMFORTABLY) will never work in GMAT as it is an adaptive test and you may/may not even get questions from your strong areas. So this makes is very important to be good at all sections. If learning formulae for you is an issue, try to understand how a particular formula came into existence , what are the assumptions etc where you can apply that particular formula, what do you need to do if you cant remember that formula etc.

Try to understand GMAT quant and there wont be any need for rote memorization. As  OptimusPrepJanielle  and  Bunuel  have mentioned above, stick to the topics above, feel free to post your questions (after checking that the same question has not been posted before) including what area(s) are you stumbling on in that question and the experts on this forum can definitely help you out.

iliavko · Answer

Thank you for your replies!

You see, if you follow the MGMAT books for example, then the info about geometry is obviously insufficient, but if you look at GmatClub math book's geometry section, you will find exotics like  L=\sqrt{A^2+(\frac{b}{2^2})}  (for triangles) So this is where I am in doubt. Should I study these formulas?..

But anyways, I am aiming for a 650, so I will try to learn as much as possible of course, but I guess these exotics will have to be left behind.

Hopefully these are unlikely to be tested.

SamirAbrahao · Answer

Based on my very limited experience (I've done only about 4 hundred quant questions altogether), you don't need to memorize any "exotics". These are the formulas I've needed to extensively practice with:

- Circle perimeter and area
- The sum of the internal angles of a given polygon
- How to calculate the largest size of a triangle
- Triangle, square and rectangle areas
- The area of some 3D forms such as cubes and rectangles

iliavko · Answer

Thank you for the reply! What about coordinate geometry? Did you pay a lot of attention to it? Or it's like "mixture problems" so you can go without it? (and guess in case you see that one question on the entire GMAT)

SamirAbrahao · Answer

As for coordinate geometry I'd say it is even more basic, but you need to have a very clear understanding of the following topics:

- The concept of slope and, on rare occasions, maybe the formula representing it
- Difference between a line and a segment, can't mess up those concepts
- x/y intersections
- Dont make assumptions based on the alphabetical order of coordinate aliases

I'm practicing with the official GMATPrep software and question packs, and I can tell you the xy-plane is present in not more than 5% of all quant section questions. I would assume that same ratio on Test Day (I haven't taken it yet) but who knows?

KarishmaB · Answer

Co-ordinate geometry is extremely conceptual. Understand points, lines, slopes, intercepts and quadrants and you can solve most questions easily.

The other topics in geometry are:
Parallel lines
Triangles - especially right triangles
Similar triangles
Polygons
Circles
3D figures - volume, surface area etc

There are a few basic formulas/concepts in each topic (about 3-4) and reviewing those is enough to solve most geometry questions.

Also, note that you may choose to ignore "mixture" questions but do not ignore the concept of weighted averages.

iliavko · Answer

Thank you very much for your reply, Karishma! Regarding the W.Average concept, I have seen it tested on percentages, something I wasn't expecting, I've also read your blog about it, it's very useful!

Today I will try to organize the percentage topic in my head.. Two weeks till the exam and I still get like 50% wrong! grr I hate percentages...

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What is REALLY important in Gmat geometry?

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