Half circle

[Ofnuts]

• Make a path which is a circle: make a circle selection and take a path from it or use a script that produces circle paths directly
  
• Edit the path with the path tool to remove half of the circle (using a guide to position the center and making sure you cirt the circle at the right place. if using a script-generated path this is somewhat easier
  
• Stroke the path in "Line" mode using "Round" caps (or in Paint tool/Paintbrush mode using a hard round brush)