z_1, z_2, z_3, z_4 are distinct complex numbers representing the vertices of a quadrilateral ABCD taken in order. If z_1 - z_4 = z_2 - z_3 and arg[ dfrac((z_4 - z_1))((z_2 - z_1))] = pi/2, then the quadrilateral is A rectangle B rhombus C square D trapezium

Let Hence Implies Hence opposites sides are parallel. Therefore its a type of parallelogram.Now .HenceAll the angles are therefore, it is rectangular a rectangle