Find the area of the shaded region.

Alright. So all I can tell from this is that the radius of the circle is 2.5

Also, the area of the square is 25.

So subtract the area of the circle from the area of the square and there you go. Only problem is I have no idea how to find the area of the circle with the given info. I know A= .5r^2theta

Is theta 90 degrees?

It doesn't seem as though I have enough info. What am I missing? Thanks