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

The magnitude of the magnetic field (B) due to the loop $A B C D$ at the origin $(O)$ is :-

A current loop $\mathrm{ABCD}$ is held fixed on the plane of the paper as shown in the figure. The arcs $\mathrm{BC}$ (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 $\mathrm{I}_{1}$ flowing out of the plane of the paper is kept at the origin.