A current I is flowing through the loop. The direction of the...

Magnetic field at the centre $M$ due to current through the curved portion $D A$ is $\vec{B}_1=\frac{\mu_0 I}{4 \pi R} \times\left(\frac{3 \pi}{2}\right)$=\frac{3 \mu_0 I}{8 R} \otimes$Magnetic field at the centre$M$due to current through the straight portion$A B$is$B_2=0$, since point$M$lies on the axis of the straight portion$A B$. Magnetic field at the centre$M$due to current through the curved portion$B C$is$\vec{B}_3=\frac{\mu_0 I}{4 \pi 2 R} \times \frac{\pi}{2}=\frac{\mu_0 I}{16 R} \otimes$Magnetic field at the centre$M$due to current through the straight portion$C D$is$B_4=0$, since point$M$lies on the axis of the straight portion$C D$. The resultant magnetic field at the point$M$is$$\begin{aligned} \vec{B} & =\vec{B}_1+\vec{B}_2+\vec{B}_3+\vec{B}_4 \\ & =\left(\frac{3 \mu_0 I}{8 R}+0+\frac{\mu_0 I}{16 R}+0\right) \otimes=\frac{7 \mu_0 I}{16 R} \otimes\end{aligned}$$