Area of equilateral triangle of side a,

$A=\frac{1}{2}\times a\times \frac{\sqrt{3}a}{2}=\frac{\sqrt{3}}{4}{a}^2$

Magnetic moment of each triangle,

$m=IA=\frac{\sqrt{3}}{4}{a}^{2}I$

$12 \mathrm{a}$ length of wire will form $4$ loops of triangle of side $a$.

Magnetic moment of triangle,

$M_1=Nm=4\times \frac{\sqrt{3}}{4}{a}^{2}I=\sqrt{3}I{a}^2$

Similarly, magnetic moment of square

$M_2=Nm=3\times \left(I{a}^2\right)$

$=3I{a}^2$