Which steps will verify that a parallelogram is a rectangle? check all that apply.
calculate the lengths of the diagonals, and show that they are equal.
calculate the lengths of all sides, and show that both pairs of opposite sides are congruent.
calculate the slope of each diagonal, and show that the lines are perpendicular.
calculate the midpoints of each diagonal, and show the diagonals bisect each other.
calculate the slopes of every side, and show that adjacent sides are perpendicular.