I'm having trouble with a geometry exercise which wants me calculate the angle y using the given angle a. The main Problem I have with the exercise is, that almost all non given and angles are varying, making it very difficult to calculate the solution.
I'm not sure if I'm missing a theorem, but I just don't see the way in which y and a are connected in a usefull way, especially considering that neither are circle chords. Can somebody help me out? Its excercise 32 btw, I'll probably just need a nudge in the rigth direction
For better understanding take a look on the item 1 and 4 here: (https://mathbitsnotebook.com/Geometry/Circles/CRAngles.html)
By central angle theorem we have $arc(CD)=\alpha$.
Then,
$$\delta=\frac{arc(CD)+arc(AB)}{2}=\frac{\alpha+180º}{2}=90º+\frac{\alpha}{2}$$