So the edge of the resulting hole in the head is (approximately) circular and the edge of the piece you've cut out is (approximately) circular.
“Dilkani Waa Mu’aamarad Ay Fuliyeen Maamulka Gobolka Saaxil Oo Si Farsamaysan Loo Hagaayay…”“Qaybta Ugu Wayna Waxaa Ka Qaatay Salaadiin Iyo Madax Dhaqameed Laakiin Cawaaqib...