Concentric Circles
Two circles are concentric if their centers coincide. The area enclosed between two concentric circles are also referred to as the annulus or circular ring.
Area of the Annulus
The area of the annulus equals the area of the larger circle minus the area of smaller circle.
Circular Trapezoid
The circular trapezoid is the area enclosed within two radii and two concentric circles.
Area of a Circular Trapezoid
The area of the circular trapezoid is equal to area of the the largest circular sector minus the area of the smaller circular sector.
Examples
A circular fountain of 5 m radius lies alone in the centre of a circular park of 700 m radius. Calculate the total walking area available to pedestrians visiting the park.
Calculate the area enclosed by the inscribed and circumscribed circles to a square with a diagonal of 8 m in length.
A regular hexagon of side 4 cm has a circle inscribed and another circumscribed around its shape. Find the area enclosed between these two concentric circles.
Two radii (plural for radius) OA and OB form an angle of 60° for two concentric circles with 8 and 5 cm radii. Calculate the area of the circular trapezoid formed by the radii and concentric circles.
