Isomeric cross-section ratios of evaporation residues formed in ₁₂C+⁹³Nb and ¹⁶O + ⁸⁹Y reactions were measured by recoil catcher technique followed by off-line 𝛾-ray spectrometry in the beam energy range of 55.7-77.5 MeV for ₁₂C and 68-81 MeV for ¹⁶O. The isomeric cross-section ratios were resolved into that for complete and incomplete fusion reactions. The angular momentum of the intermediate nucleus formed in incomplete fusion was deduced from the isomeric cross-section ratio by considering the statistical de-excitation of the incompletely fused composite nucleus. The data show that incomplete fusion is associated with angular momenta slightly smaller than critical angular momentum for complete fusion, indicating the deeper interpenetration of projectile and target nuclei than that in peripheral collisions.