A cyclic quadrilateral test

You will write the opposite angle of a cyclic quadrilateral, and a test for whether four angles can belong to one.

Your tasks.

1. In opposite, return the angle opposite to a given angle: $180^\circ$ minus it.
2. In is_cyclic, return True when a + c and b + d are both $180$, and False if not.
3. Set d_angle to the angle $D$ of a cyclic quadrilateral with $A = 82$, $B = 97$ and $C = 98$. Use your function.