A non-planar loop of conducting wire carrying a current I is placed as shown in the figure.  Each of the straight sections of the loop is of length 2a. The magnetic field due to this loop at the point P (a, 0, a) points in the direction
 

We can consider the non- planar loop as made by two loops ABCDA and AQRBA as shown in figure

Magnetic field due to loop ABCDA will be along x-axis and due to loop AQRBA along z-axis, magnitude of magnetic field due to both loops will be equal 

Therefore, direction of resultant magnetic field at P will be along $\frac{1}{\sqrt{2}}(\widehat{\mathrm{i}}+\widehat{\mathrm{k}})$