Are all angles of a parallelogram congruent?

All angles of a parallelogram are not necessarily congruent. A parallelogram means that the opposite sides run in straight lines that don't intersect. An example is a rectangle or square. Length of sides DO NOT determine if opposite angles are congruent. As long as opposite sides do not intersect each other at any point (if you continue to draw the lines), then the angles diagonal from each other are the same.