I assume you mean all the purple parts is what you want selected? Since much of the purple at the edges is the same colour as the background you may have no other recourse than to select it manually. I wouldn't use the scissors select but most other select tools should do it.
EDIT:- Or if it is just the centre you want (the outer circle & triangle inwards) You could - select the circle (with the ellipse select) near the triangle points, select to path, edit the path to add the triangle points then path to selection, invert your selection and delete.
EDIT:- Or if it is just the centre you want (the outer circle & triangle inwards) You could - select the circle (with the ellipse select) near the triangle points, select to path, edit the path to add the triangle points then path to selection, invert your selection and delete.
