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If the length of side AB is 17, is triangle ABC a right triangle?

(1) The length of side BC is 144.

(2) The length of side AC is 145.

Can someone explain what would be correct answer for this?

This was a good one .
Instead of calculating squares ( which gmat will never ask you ) , I did a quick calculation ie 145^2 - 144^2 = (145-144)(145 +144 ) = 289
which is square of 17.
So it does means a triangle with 17 144 145 is right angle triangle . But this does not mean that answer is C . But now if we know that one of side 144 or 145 it has to be a right angle triangle .
So answer is D

But this does not mean that answer is C . But now if we know that one of side 144 or 145 it has to be a right angle triangle . So answer is D

Why do u say that? My original answer was C. But I gave this a thought after reading ur answer but decided, just knowing two sides and no angles would be useless.

But this does not mean that answer is C . But now if we know that one of side 144 or 145 it has to be a right angle triangle . So answer is D

Why do u say that? My original answer was C. But I gave this a thought after reading ur answer but decided, just knowing two sides and no angles would be useless.

It is simply impossible to conclude on the type of a triangle by knowing just 2 sides. It has to be C

It has to be C. And, to save time, there is no need to calculate if it is a right triangle or not.

1) Ins. - you know 2 sides, no angles

2) Ins. - same reasoning

Together you have 3 sides and it either follows the pythagreon theorem or doesn't. The answer doesn't matter if its yes or no, just if it can be solved.

It has to be C. And, to save time, there is no need to calculate if it is a right triangle or not.

1) Ins. - you know 2 sides, no angles

2) Ins. - same reasoning

Together you have 3 sides and it either follows the pythagreon theorem or doesn't. The answer doesn't matter if its yes or no, just if it can be solved.

ah. the more of these I read the more these make sense.

It has to be C. And, to save time, there is no need to calculate if it is a right triangle or not.

1) Ins. - you know 2 sides, no angles

2) Ins. - same reasoning

Together you have 3 sides and it either follows the pythagreon theorem or doesn't. The answer doesn't matter if its yes or no, just if it can be solved.

Great answer! I need to remember that for a DS all you need to know is whether or not you can solve it (or answer the yes/no question). The less actual math to do, the better!