With spin...

Select the vertexes you wish to spin,  place the 3D cursor at the desired center of the rotation, Under mesh tools, adjust the degrees of rotation and the number of steps.  Click the spin button and with the 'Question Mark' mouse cursor, click on your object.

The the vertexes will spin around the 3D Cursor - based on the current view.  If you change your view from front to side, it will rotate the vertexes in a different direction.

Reddog9
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