The magnetic field at the centre of an equilateral triangular loop of side 2L and carrying a current i is
9μ0i4πL
33μ0i4πL
23μ0iπL
3μ0i4πL
Magnetic field at O is
B=3 μ04π ir sin 600 + sin 600
=3 μ04π i 3L 3= 9μ0i4πL