Annulus is the area between the two concentric circles having different radii.
A ring-shaped object is called as 'annulus' in Latin.
Area (A) between two concentric circles with outer radius R and inner radius r is given by, A = Π(R2 - r2).
Two concentric circles with outer radius R and inner radius r are shown in the figure. The region shaded with green color is annulus.
A. 38Π square cm
B. 37Π square cm
C. 36Π square cm
D. 40Π square cm
Correct Answer: C
Step 1: Required Area = Area of outer circle - Area of inner circle
Step 2: Required Area = Π(10)2 - Π(8)2 [Use circle area formula and substitute.]
Step 3: Required Area = Π(100 - 64) = 36Π square cm [Simplify.]