Which of the following statements about parallelograms are true?
Select all that apply. (You should have more than one answer choice selected.)
a
all angles of a parallelogram add up to 360 degrees
b
all sides of a parallelogram are parallel
c
all parallelograms are rectangles
d
opposite angles of a parallelogram are congruent
e
opposite sides of a parallelogram are congruent
f
all rectangles are parallelograms