Diameter of Lawn = 28 cm
Length of rope tied at the centre of lawn = 7cm.
As the cow, tied to the rope grazes the lawn it forms a circle with radius 7cm.
Area of lawn grazed by cow
= pi*7^2. ( pi = 3.14)
= 3.14 * 49
= 153.86 sq. cm
Area of the lawn with radius 14 cm
= pi * 14^2. (pi = 3.14)
= 3.14 * 14^2
= 615.44 sq cm
Remaining area = Area of the Lawn - Area of the lawn grazed by cow
= 615.44 - 153.86
= 461.58 sq cm