Length of rectangular field = L = 70 m
Breadth of rectangular field = B = 52 m
So, Area of the field = L x B
= 70×52 = 3640
Area of the field is 3640 m2
And, Area of quadrant of radius 21 m = 1/4 x 22/7 x 21 x 21
= 346.5 m2
Area available for grazing = (Area of the field) – (Area of quadrant of radius 21 m)
= 3640 – 346.5
= 3293.5 m2
Thus, 3293.5 m2 area is left ungrazed.