Answer:
15 units by 15 units
Step-by-step explanation:
Recall that the formula for the area of a square is A = s^2, where s is the length of one side.
Here, A = s^2 = 225 units^2.
Taking the sqrt of both sides, we get s = +15 units.
Thus, the panel here is 15 units long and 15 units wide.
