A horse is tied to a pole with 28 m long string.

We know that the horse is tied to a pole with 28 m long string. So the horse can graze the area of a circle of radius 28 m.

Area of circle is

$A=\pi r^{2}$

$=\frac{22}{7} \times 28 \times 28 \mathrm{~m}^{2}$

$=2464 \mathrm{~m}^{2}$

Hence the horse can graze $2464 \mathrm{~m}^{2}$ area.