Question: Triangle Area

Comment on Triangle Area

Hi Brent,

In statement 2, we have two values, one is satisfying and the other doesn't. So, is it correct to consider the whole statement is correct since only one value satisfies the statement?

Can you please share me some more examples of such kind.Because till now I have seen that only if all values satisfy any statement only then that statement is considered correct. Please brief me your inputs on this.
gmat-admin's picture

Be careful. The question isn't asking us to determine the value of y. The question asks us to determine the area of the triangle. So, although statement 2 yields two possible values of y, this does not mean there are two possible areas. As we see in the video, one of the y-values does not produce a viable triangle, so we must disregard that y-value.

Here an analogous question:
If x = the number of arms that Joe has, what is the value of x?
(1) x^2 = 4
Is this statement sufficient?
Well, the equation tells us that EITHER x = 2 OR x = -2
However, one x-values (x = -2) makes no sense when it comes to the number of arms a person can possess. So, we can disregard this value, and conclude, with certainty, that x = 2.
So, even though statement 1 yields two possible x-values, it yields only ONE answer to the target question. So, statement 1 is sufficient.

Hello, What level is this question ? is that what geometry 700+ looks like ?
gmat-admin's picture

Yes, this would be a 700+ level geometry question on the GMAT.

Brent, could we also say that the length cannot be equal to 5 as the hypotenuse of the triangle is already 5?
gmat-admin's picture

Absolutely. The height of the triangle divides triangle ABC into 2 right triangles. So, if y = 10, then the length of one leg = 5, and the hypotenuse (5) must be longer than each leg.

Hi Brent, For statement 1. Where y = 6 why is the height 3 instead of 4. Are three and four interchangeable numbers on a right triangle.
gmat-admin's picture

In the video I explain that, for statement 1, y can equal either 6 or 8.

If y = 6, then the height of the triangle divides triangle ABC into two equal right triangles. Both of these right triangles have a base of length 3 and a hypotenuse of length 5. Applying the Pythagorean Theorem, we can conclude that the height of the triangle must be 4.

If y = 8, then the height of the triangle divides triangle ABC into two equal right triangles. Both of these right triangles have a base of length 4 and a hypotenuse of length 5. Applying the Pythagorean Theorem, we can conclude that the height of the triangle must be 4.

Does that help?

ari.banerjee's picture

what a mind boggling qs.

I chose C initially. But there are so many details to consider in a DS question and it keeps finding a way to surprise me lol
gmat-admin's picture

Mind-boggling indeed!! It's one of the toughest questions on the site.

Cheers,
Brent

Ahhhhhhh!!! It's these sorts of questions where we have to fully solve to the end in order to get right answer! I chose C too :-)

They have asked the area and by substituting either 6 or 8, we get the same answer. It is a DS question, so I skip the calculations part but now I think I will have to calculate for all DS questions too!!
If they ask only the value of y, then the option should be B right?
gmat-admin's picture

That's correct. If the target question asked "What is the value of y, the correct answer would be B.

Hi Brent,

Can you please help with the following question:

https://gmatclub.com/forum/approximately-what-percent-of-the-area-of-the-circle-shown-i-169744.html#p1352630
gmat-admin's picture

Hi Brent, if there are 2 equal sides in a triangle, can I always assume that it must be a 45, 45 90 triangle?
gmat-admin's picture

IF we're told the isosceles triangle is a RIGHT triangle, then it must be a 45-45-90 special triangle.
However, if we're NOT told the isosceles triangle is a right triangle, then it COULD be a 45-45-90 special triangle, or it could be some other isosceles triangle such as a 10-10-160 triangle or a 70-70-40 triangle.

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