Clearly, the diagonal AC of the rhombus divides it into two congruent triangles.

For triangle ABC, a = b = 30 m, c = 48 m.

∴ s = a +b + c/ 2 = 30 +30 + 48 /2 m = 54 m

∴ Area of the rhombus = 2 × 432 m^{2} = 864 m^{2}

Number of cows = 18

Hence, area of the grass field which each cow gets

= 864/ 18 m^{2} = **48 m**^{2} Ans.