For an arc length s, area of sector A, and central angle of a circle of radius r, find the indicated quantity for the given value. A= 51.1 mi ^2 , R=...

For an arc length s, area of sector A, and central angle

​ , R= 51.1 mi,

I know that the formula is A= R​ ​

I know that the formula looks like this for the problem

​/(51.1 mi)​

However when I type it into my calculator it is giving me the incorrect answers. Does anyone know what I am doing wrong or can anyone please help me figure this out?