Given, in a parallelogram ABCD, the bisector of angle C and D meet at O.

Since we know that the sum of adjacent angles in a parallelogram is 180

=> ∠A + ∠B = 180

=> 2x + 2y = 180

=> 2(x + y) = 180

=> x + y = 180/2

=> x + y = 90   ....................1

Again, in triangle COD,

      x + y + ∠COD = 180    {since sum of angles in atriangle is 180}

=> 90 + ∠COD = 180

=> ∠COD = 180 - 90

=> ∠COD = 90

So, The angle COD is 90 degree.