2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57079For submanifolds tangent to the structure vector field in cosymplectic space forms, we establish a basic inequality between the main intrinsic invariants of the submanifold, namely its sectional curvature and scalar curvature on one side; and its main extrinsic invariant, namely squared mean curvature on the other side. Some applications including inequalities between the intrinsic invariant $δ_{M}$ and the squared mean curvature are given. The equality cases are also discussedLatex 9 pagesMathematical PhysicsDifferential Geometry53C40, 53D15text