Now that you’ve mastered GMAT Geometry, it’s time to let the world know!

- Video Course
- Video Course Overview - READ FIRST
- General GMAT Strategies - 7 videos (all free)
- Data Sufficiency - 16 videos (all free)
- Arithmetic - 38 videos (some free)
- Powers and Roots - 36 videos (some free)
- Algebra and Equation Solving - 73 videos (some free)
- Word Problems - 48 videos (some free)
- Geometry - 42 videos (some free)
- Integer Properties - 38 videos (some free)
- Statistics - 20 videos (some free)
- Counting - 27 videos (some free)
- Probability - 23 videos (some free)
- Analytical Writing Assessment - 5 videos (all free)
- Reading Comprehension - 10 videos (all free)
- Critical Reasoning - 38 videos (some free)
- Sentence Correction - 70 videos (some free)
- Integrated Reasoning - 17 videos (some free)

- Study Guide
- Office Hours
- Extras
- Guarantees
- Prices

## Comment on

Right Triangles## Your answer is incorrect on

## That's true. However, when

That's true. However, when real world questions, we have to remember that the length of a side of a triangle cannot be negative. So, we must ignore the negative solution.

## I don't get it. Why not just

## Calculators are not permitted

Calculators are not permitted in the quantitative section of the GMAT.

## Hi Brent,

First of all, I really like your videos and explanation of each question.

I am little skeptical about this question.

Link : https://gmatclub.com/forum/right-triangle-abc-has-sides-with-length-x-y-and-z-if-triangle-abc-236889.html

Question:

Right triangle ABC has sides with length x, y and z. If triangle ABC has perimeter 17, and x² + y² + z² = 98, then what is the area of triangle ABC?

A) 12.75

B) 13.25

C) 14

D) 14.5

E) 15.25

I saw your response on gmatclub. My confusion is, how can we say for sure that z is the hypotenuse. Couldn't it be either x or y?

## Link: https://gmatclub.com

Link: https://gmatclub.com/forum/right-triangle-abc-has-sides-with-length-x-y-...

Since triangle ABC is a right triangle, we know that one of the lengths (x, y or z) is the length of the hypotenuse. Since the question is asking for area (and not asking for the specific value of one of the variables), I just let z = the length of the hypotenuse

I could have just as easily chosen x or y to be the length of the hypotenuse, and it wouldn't have changed the solution. Try it, and you'll see.

## Here is where my confusion

I understand I can square the first equation and make it into quadratic and then solve, but i do not understand why my method above fails. Any advice?

## You're referring to this

You're referring to this question: https://gmatclub.com/forum/right-triangle-abc-has-sides-with-length-x-y-...

I'd need to see your calculations to see where things went wrong.

Here are my calculations:

Take x² + y² = 49 and replace y with (x - 10)

We get: x² + (10 - x)² = 49

Expand: x² + 100 - 20x + x² = 49

Simplify: 2x² - 20x + 100 = 49

Rearrange: 2x² - 20x + 51 = 0

The solution to this is not pretty.

IMPORTANT: our goal here is to find the value of xy/2. So, rather than try to solve this awful equation, we should probably look for different approach.

Aside: We COULD solve the above equation for x and then use that x-value to determine the value of y. At that point, we could determine the value of xy/2. The problem is that the numbers are very awful to work with.

## Can you please answer this

## Question link: https:/

Question link: https://gmatclub.com/forum/a-certain-right-triangle-has-sides-of-length-...

You bet.

Here's my solution (with diagram :-): https://gmatclub.com/forum/a-certain-right-triangle-has-sides-of-length-...

## Hi Brent,

I was referring to Bunuel's solution to this Q : https://gmatclub.com/forum/in-the-figure-each-side-of-square-abcd-has-length-1-the-length-of-li-54152.html#p1034198

In problems such as these, I fail to come up with the first step, viz. extending EC to EO, making the diagram favorable for application of known properties and theorems. Its not that I don't know the Geometry rules and properties well. I know about special right triangles, properties of square such as "Diagonals bisect at 90 deg", "Diagonals bisect vertical angles". Yet its really frustrating for me to not be able to come up with the first step as I am easily able to solve the problem once I have the reconstructed drawing.

I am currently at Q49 and it is such lack of intuition that is preventing me from achieving Q50-51. Hence I am seeking your advice as you are an expert and must have helped students going through a similar concern. How do I build the intuition required to solve such problems? Or do I simply concede that such Qs are beyond my ability and move on?

Thanks & Regards,

Abhirup

## Hi Abhirub,

Hi Abhirub,

How to build intuition. TOUGH question!

It's important to keep in mind that, there is a finite number of mathematical strategies (even outside-the-box strategies) that are applicable to solving GMAT math questions.

So, as you study more and more practice questions AND more solutions (reviewing solutions is key here), you will add more and more strategies to your mathematical toolbox.

Cheers,

Brent

## Add a comment