Proving Rectangles

A rectangle is a parallelogram with

• All sides the same
• All angles the same
• Diagonals that are perpendicular

To prove a shape is a rectangle you usually first must know

• That the shape is a parallelogram
• What today's date is
• That the shape has 4 sides congruent
• That the shape is isosceles

Which of the following is not a way to prove a shape is a rectangle?

• prove it's equiangular
• prove it's a parallelogram, then prove that it has 1 right angle
• prove it's a parallelogram, then prove the diagonals are congruent
• prove it's a parallelogram, then prove opposite angles are congruent