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Create a circle, change to Editable Shapes, remove one control point to get a semi-circle, remembering to Make line (L) with the two end points..
Clone that and rotate the required angle around the...

slast, I would do it differently.

With the Shape Tool selected, set Make Line and Cusp Join (press LZ).
Click three random points.
Press Tab to select the mid-point control.
In the Line Angle...