Please help me please

Answer:
B
Step-by-step explanation:
So we have a 45-45-90 triangle.
This is a special right triangle. In a 45-45-90 triangle, the side lengths are x, and the hypotenuse will be x√2
Since the hypotenuse is 3, we can set it equal to x√2 to solve for x. Therefore:
[tex]x\sqrt2=3[/tex]
Divide both sides by √2:
[tex]x=\frac{3}{\sqrt2}[/tex]
Rationalize:
[tex]x=\frac{3\sqrt2}{2}[/tex]
Our answer is B.