code: function (x, y, rad) {
            var X = x * Math.cos(rad) - y * Math.sin(rad),
                Y = x * Math.sin(rad) + y * Math.cos(rad);
            return {x: X, y: Y};
        }
docs: for more information of where this math came from visit: http://www.w3.org/TR/SVG11/implnote.html#ArcImplementationNotes