 The area of the rectangle is

and the area of a single orange triangle is

Therefore, the area of the parallelogram is

Another area formula, for two sides "B" and "C" and angle θ, is

The area of a parallelogram with sides "B" and "C" ("B" ≠ "C") and angle formula_6 at the intersection of the diagonals is given by

When the parallelogram is specified from the lengths "B" and "C" of two adjacent sides together with the length "D"1 of either diagonal, then the area can be found from Heron's formula.Specifically it is

where formula_9 and the leading factor 2 comes from the fact that the chosen diagonal divides the parallelogram into "two" congruent triangles.Let vectors formula_10 and let formula_11 denote the matrix with elements of a and b.