Answer:
B. 6√2
Explanation:
We can use the Pythagorean Theorem to solve this out. The Pythagorean Theorem states that for any right triangle with the shortest sides (called legs) as a and b and the longest side (called the hypotenuse) as c:
a² + b² = c²
Here, a = b = 6, so:
6² + 6² = c²
36 + 36 = c²
72 = c²
c = √72 = 6√2
Now, we see the answer is B.
However, there's a trick to solving these kinds of problems. Notice that DEF is both an isosceles triangle and a right triangle. We call these 45-45-90 triangles because those are the angles of the triangle.
One characteristic of these types of triangles is that their leg to leg to hypotenuse ratio is 1 : 1 : √2, always. We could apply that here. We see that the legs are 6, so we could find the hypotenuse simply by multiplying 6 by √2, and we would get 6√2, which is exactly the value we obtained above.
Thus, the answer is B.