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CT2b Angle in a semicircle

Second circle theorem:

Worth having a look at CT2a first; then... What happens to angle α as you move P? (Bit dull, as I expect you've worked out that there is an angle bigger than acute, but smaller than obtuse....)
If you need it, this theorem is set out here and all the theorems are summarised here Tim Devereux, Created with GeoGebra