Let "M" be the projectivization of the cotangent bundle of "N": thus "M" is fiber bundle over a "M" whose fiber at a point "x" is the space of lines in T*"N", or, equivalently, the space of hyperplanes in T"N". The 1-form λ does not descend to a genuine 1-form on "M". However, it is homogeneous of degree 1, and so it defines a 1-form with values in the line bundle O(1), which is the dual of the fibrewise tautological line bundle of "M". The kernel of this 1-form defines a contact distribution.