Regiomontanus' Problem

Regiomontanus wanted to know where the best place on earth would be to observe Saturn.
Which resolves itself into the question of finding a value for angle EAC which maximizes the angle CED.
Use trial and error to find a good value for EAC.

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CD
AC
EAC
CED

Turn on the circumcircle once you have found this value. What do you observe?
Try other values for AC and CD.

App generated by Geometry Expressions