In the diagram above, ABCD is a square with side M, and EFGH is a squa

Hi Lucky2783

Could you please explain why the 4 triangles are congruent?

Hi Naina1,

The reason why the 4 triangles are congruent involves a few geometry rules:

1) The angles on a line sum to 180 degrees
2) The angles in a triangle sum to 180 degrees
3) The corners of squares are 90 degree angles.

To prove the point, I'm going to have you do a little work....

1) Start with the purple triangle in the drawing and select two values (you get to choose) for the two non-90 degree angles. Remember that you're dealing with a triangle, so the sum of the angles has to be 180 degrees.
2) Next, working clockwise or counter-clockwise, figure out the next angle (remember, the corners of squares are 90 degrees and lines must sum to 180 degrees).

As you keep working, you'll find that each of the other triangles has the exact same angles (and side lengths) as the purple one.

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

Please see attached.
one right angle.
one side of triangle i.e. Hypotnuse
and the highlighted angle are equal

VERITAS PREP OFFICIAL SOLUTION:

In the diagram, we literally have two squares, M squared and K squared. The four right triangle are what we get if we subtract one square from the other: they are literally the difference of two squares, so we can use the Difference of Two Squares formula:

M^2 - K^2 = (M + K)(M - K)

We could find (M + K) if we knew (M – K) and the difference of the squares.

Statement #1: this gives us (M – K), but we don’t know the difference of the two squares. This statement, alone and by itself, is not sufficient.

Statement #2: this gives us the area of one triangle, and if we multiply by 4, we have the difference of the two squares. But, now we don’t know (M – K), so we can solve. This statement, alone and by itself, is not sufficient.

Combined statements. With the two statements, we know both (M – K) and the difference of the squares, so we can solve for (M + K). Together, the statements are sufficient.

Answer = (C)

What are the correct values for M and K? Solved it in a different way and would like to know if my calculation was correct or if i just correctly guessed C. Much appreciated!

1. we can't get any info from here
2. we can find AE, AH, and side of the inner square - K. but we don't know for M.

1+2 - we know K, we can find M. sufficient.

Statement 1 is insufficient because it does not give us anything relevant m-k = 9

Statement 2 is insufficient but is helpful in the following way:
We know the area of bigger square = m^2
Area of smaller square is K^2
We can infer that M^2 = K^2 + (4*36) {area of smaller square plus area of 4 triangles}

This gives us M^2 - K^2 = 144
(M-K)(M+K) = 144

To solve we can get M-K from first statement so C is sufficient