$(a)\;\sin ^{-1} \bigg( \frac{\lambda}{d}\bigg) \\ (b)\;\sin ^{-1} \bigg( \frac{\lambda}{3d}\bigg) \\ (c)\;\sin ^{-1} \bigg( \frac{\lambda}{2d}\bigg) \\ (d)\;\sin ^{-1} \bigg( \frac{\lambda}{4d}\bigg)$