Answer:
D
Explanation:
This is a 45 45 90 triangle
It is special because the sides are in a certain ratio of 1:1:

is the length of the hypotenuse and 1 is the length of the legs.
This means that the length of the legs are equal, so y=

If 1 part is
, we need to find what
is.
We can do that with
*

6
x=6