Let us consider ABCD be a rectangular field.
Given, Length of the field =
m
Given, Breadth of the field =
m
From the given question,
A cow is tied with a rope at a point A.
Let us consider length of rope be AE =
m = l.
We know that Angle subtended at the centre of the sector =
Now for Angle subtended at the center (in radians)
=
=
∴ Area of a sector of a circle =
=
=
Therefore, the area of the field in which cow can graze is