# CT2a Discovering 'angle in a semicircle'

- Author:
- Tim Devereux

Second circle theorem:
Try moving the point P about. Where does P have to
be for angle α to be acute? and where must P be for angle α to be
obtuse? So where must P be to make angle α = 90 degrees?

(Now go on to CT2b - the other Geogebra worksheet for the second circle theorem)