ANS : B

lets say we have an isoceles triangle ABC with B = 90 degress and AB=BC=X and CA=Y.

now applying rt angle formula sqr Y = sqr X + sqr X = 2(sqr X).......................1
also, perimeter = 2X + Y = 16 + 16(sqrt of 2).................2

solve both the equations for Y.. in the end, we would get the equation something like:

Y + Y(sqrt 2) = 16 + 16(sqrt 2).

From this, its easily seen that Y=16.

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Remember the equation for isoscelleous right triangle sides- x:x:x*sqrt(2)

Let one leg= a Thus,
2a+sqrt(2)*a= 16+16*sqrt(2)

Readjusting
2a+sqrt(2)*a= 16*sqrt(2)+16

thus a = 8 *sqrt(2)
And hypotenus= 16

Ans:- B

Hey guys,

Nice solution - just one thing I like to point out on these:

Think like the testmaker!

If I were writing the test and knew that everyone studies the 45-45-90 ratio as: 1, 1, sqrt 2

I would make a living off of making the shorter sides a multiple of sqrt 2 so that the long side is an integer. People aren't looking for that! And they often won't trust themselves enough to calculate correctly...they'll look at the answer choices and see that 3 of them are Integer*sqrt 2, and they'll think they screwed up somehow because the right answer "should" have a sqrt 2 on the end.

So...keep in mind that with the Triangle Ratios:

45-45-90
x: x: x*sqrt 2

30-60-90
x : x*sqrt3 : 2x

One of the easiest tricks up the GMAT author's sleeve is to make x equal to a multiple of the radical so that the radical appears on the side you're not expecting and the integer shows up where you think it shouldn't!

Also, as you go through questions like these, ask yourslf "how could they make that question a little harder" or "how could they test this concept in a way that I wouldn't be looking for it". Training yourself to look out for unique cases, from the testmaker's perspective, helps you to get a real mastery of the GMAT from a high level.
_________________

Brian

Veritas Prep | GMAT Instructor

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