Areal=(R^2⋅π)−(r^2⋅π)A r e a l = ( R 2 ⋅ π ) − ( r 2 ⋅ π )
Eller
Areal=(R^2−r^2)⋅πA r e a l = ( R 2 − r 2 ) ⋅ π
R: Den store cirkels radius r: Den lille cirkels radius
