
The
total strength of magnetic field at the center = 3 times the magnetic
field at the center due to any one side. (since this is an equilateral
triangle).
Magnetic field due to any one side as shown in the figure =

where R is the perpendicular distance of the wire from the center which is

therefore,
total magnetic strength is

Thanks and Regards
Apoorva Arora
IIT Roorkee
askIITians Faculty