so hmmm the diagonals of a rhombus, bisect each other angles, and thus, they cut each other in halves, and they're also perpendicular to each other, check the picture below
so, they end up forming 4 equal triangles
so, just get the area of each of the triangles, and sum them up, that's the area of the rhombus
or the area of one of the triangles, and multiply it times 4, same thing
