Hi All,

We're told that triangle LMN is an isosceles triangle. We're asked for the PERIMETER of that triangle.

1) Side LM has a length of 4

With the information in Fact 1, we know that one (or possibly two) of the sides of this isosceles triangle, but we don't know all 3 sides, so the perimeter of the triangle could be more than one possible number.
Fact 1 is INSUFFICIENT

2) Side MN has a length of$$ 4\sqrt{2}$$

With the information in Fact 2, we know that one (or possibly two) of the sides of this isosceles triangle, but we don't know all 3 sides, so the perimeter of the triangle could be more than one possible number.
Fact 2 is INSUFFICIENT

Combined, we know...two of the sides - and that one of those numbers is the third side. That still leaves us with 2 possible values:
4 + 4 + sqrt{2}
or
4 + sqrt{2} + sqrt{2}
With two different possibilities for the perimeter, we don't know which one actually is the perimeter.
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorDC wrote:What is the perimeter of isosceles triangle LMN?

1) Side LM has a length of 4

$$(2)Side\ MN\ has\ a\ length\ of\ 4\sqrt{2}$$

OA E

Source: Veritas Prep

Target question: What is the perimeter of isosceles triangle LMN?
Jump to. . . .

Statements 1 and 2 combined
There are two triangles that satisfy BOTH statements. They are:
Case a: The side lengths of triangle LMN are 4, 4 and 4√2. In this case, the answer to the target question is the perimeter = 4 + 4 + 4√2 = 8 + 4√2
Case b: The side lengths of triangle LMN are 4, 4√2 and 4√2. In this case, the answer to the target question is the perimeter = 4 + 4√2 + 4√2 = 4 + 8√2
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent