Calculate SVG arc for circle

                    function polarToCartesian(centerX, centerY, radius, angleInDegrees) {
                        var angleInRadians = (angleInDegrees - 90) * Math.PI / 180.0;

                        return {
                            x: centerX + (radius * Math.cos(angleInRadians)),
                            y: centerY + (radius * Math.sin(angleInRadians))
                        };
                    }

                    function describeArc(x, y, radius, startAngle, endAngle) {
                        var start = polarToCartesian(x, y, radius, endAngle);
                        var end = polarToCartesian(x, y, radius, startAngle);

                        var largeArcFlag = endAngle - startAngle <= 180 ? '0' : '1';

                        var d = [
                            'M', start.x, start.y,
                            'A', radius, radius, 0, largeArcFlag, 0, end.x, end.y
                        ].join(' ');

                        return d;
                    }
                    var degrees = 180;
                    element.find('#arc1').attr('d', describeArc(100, 100, 80, 0, degrees));