Work out quadrilateral area instantly with clear inputs, formula shown and shareable results.
Any quadrilateral splits into four triangles along its diagonals, and summing them gives A = ½·d₁·d₂·sin θ where θ is the angle between the diagonals. The enclosing parallelogram formed by lines through the vertices parallel to the diagonals has exactly twice this area.
Area from diagonals
A = ½ · d₁ · d₂ · sin θ
It works whenever the diagonals actually intersect inside the figure. For a re-entrant shape use the shoelace formula with the four vertices instead.
sin θ = 1 and the formula reduces to ½·d₁·d₂, the rhombus and kite case.