>>11261676I assume you mean at point O? The circular part of the loop produces a field going into the page, the straight segment produces a field going out of the page. The contribution of the circular arc is simply proportional to the circular arc length B=i*(2*pi-theta)*R while the contribution of the straight segment must be calculated using biot savart law. Whichever of the two comes out greater will give your answer, but in general it depends on the value of theta. If picture is drawn more or less to scale answer would be into the page.
