Use rotations to prove properties of parallelograms. Move Points A and B to make different paralllelograms. The triangle with the red vertices rotates around the green point. Use the slider to rotate the triangle. While the angle of rotation is set to 0 degrees move the red triangle and the point of rotation any where you like.
Can you identify any angles or segments that are congruent? Can you identify any triangles that are congruent? How do you know that the figure is a parallelogram?