Any quadrilateral

Four straight sides, none necessarily parallel. Any convex quadrilateral can be measured from its two diagonals and the angle between them.

Units

Dimensions

diagonal p5diagonal q4angle between diagonals (°)70

Results

area A

Formulas

The diagonals cut it into four triangles; adding their areas, the pieces of the diagonals regroup into p and q, whatever the crossing point.

Checked: the A formula agrees with a Monte Carlo measurement of the shape itself, made from its geometric definition, every time the site is built.

Topology lens

Topologically a disc, like every figure here without a hole: Euler characteristic 1. Stretching turns it into a circle, a square or a star. More on the lens.