Trey, Amelia, and Cho are discussing the solution set to the equation x^2 + 9 = 45.

To find the correct solution to the equation \( x^2 + 9 = 45 \), we first need to solve for \( x \).

1. Start by isolating \( x^2 \):
\[
x^2 + 9 = 45
\]
Subtract 9 from both sides:
\[
x^2 = 45 - 9
\]
\[
x^2 = 36
\]

2. Next, take the square root of both sides:
\[
x = \pm \sqrt{36}
\]
Which gives us:
\[
x = 6 \quad \text{or} \quad x = -6
\]

Thus, the solution set is \( \{-6, 6\} \).

Now, let's evaluate the given statements:

- Trey says the solution is {6}. (Incorrect)
- Amelia says the solution is {-6, 6}. (Correct)
- Cho says the solution is {-6}. (Incorrect)

The person who has found the correct solution set is **Amelia**.