The magnitude of the magnetic field (B) due to the loop

The magnitude of the magnetic field (B) due to the loop $\mathrm{ABCD}$ at the origin $(\mathrm{O})$ is :-

A current loop ABCD is held fixed on the plane of the paper as shown in the figure. The arcs BC (radius $=b$ ) and DA (radius $=a$ ) of the loop are joined by two straight wires AB and CD. A steady current $\mathrm{I}$ is flowing in the loop. Angle made by $\mathrm{AB}$ and $\mathrm{CD}$ at the origin $\mathrm{O}$ is $30^{\circ}$. Another straight thin wire with steady current $I_{1}$ flowing out of the plane of the paper is kept at the origin.