English
The area form on a real two-dimensional oriented inner product space is defined in terms of a standard construction from the volume form and orientation.
Русский
Площадной формой на ориентированном двумерном вещественном скалярном произведении является форма, производная от объема и ориентации.
LaTeX
$$$\omega = \text{areaForm}(o)$$$
Lean4
/-- An antisymmetric bilinear form on an oriented real inner product space of dimension 2 (usual
notation `ω`). When evaluated on two vectors, it gives the oriented area of the parallelogram they
span. -/
def areaForm :=
val_proj @wrapped✝.{}