Properties of parallelogram -
∠A + ∠D = 180⁰,
∠D + ∠C = 180⁰
∠C + ∠B = 180⁰,
∠B + ∠A = 180⁰
a) It’s opposite sides are equal.
b) It’s opposite angles are equal
c) It’s diagonals bisects each other
d) Each of its diagonals divides it into two congruent triangles.