In ABCD, ∠A = 72°

We know that opposite angles of a parallelogram are equal.
Hence, ∠A ​= ∠C and ∠B ​= ∠D ​ ​
∴ ∠C = 72°
∠A and ∠B are adjacent angles.
∴ ∠A ​+ ∠B​ = 180°
∠B = 180°° − ∠A
​ ∠B​ = 180° − 72° = 108°
∴​ ∠B​ =​ ∠D = 108°
Hence, ∠B​ =​ ∠D = 108°​ and ∠C​ = 72°