A rhombus. (Looks like a diamond.)
Draw a square / rectangle, a quadrangle is just a shape with 4 sides, as long as one is a right angle your golden
I am a rectangle
A parallelogram or a rhombus
The answer depends on what it is that is being summed: the length of the sides or diagonals, the angle measures, something else.
Such a quadrangle cannot exist. The right angle must be formed by one of the parallel sides and one of the non-parallel sides. Then the angle formed at the other end of that non-parallel side would also be a right angle (the non-parallel side would be a transversal intercepting the two parallels). But then the quadrangle has two right angles, and not just one. No its Trapezoid
A rhombus is a quadrilateral in which all of the sides are of equal length, It is an equilateral quadrangle. If any angle of an equilateral quadrangle is a right angle, then all its angles are right angles. It is also a square. All squares are rhombuses. Some rhombuses are squares. A rhombus is a parallelogram with 4 congruent sides. A square is a rhombus with 4 congruent angles.