d
\(d \tan 60^{\circ}=2 \sqrt{3}\)

\(d =2\,cm\)

\(B =3 \times \frac{\mu_0 i }{2 \pi d } \sin 60^{\circ}\)

\(=3 \times \frac{2 \times 10^{-7} \times 2}{2 \times 10^{-2}} \times \frac{\sqrt{3}}{2}\) \(=3 \sqrt{3} \times 10^{-5}\)