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 mi2 , R= 51.1 mi, = ?

I know that the formula is A=1/2 R2 and to solve for the formula is =2A/R2

I know that the formula looks like this for the problem

= 2 * 51.1 mi2/(51.1 mi)2

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?