Answer:
Step-by-step explanation:
Define a cyclic quadrilateral by a quadrilateral that is circumscribed by a circle. In this case, since the quadrilateral shown is circumscribed by a circle, it is a cyclic quadrilateral.
A property of all cyclic quadrilaterals is that their opposite angles are supplementary, meaning they add up to 180 degrees. Since and
are opposite angles in the quadrilateral, they must be supplementary. Therefore, we have the equation: