code: function doCalc() {
              var distance = lengthMeasurer.getLength(pathPositions, false, WorldWind.GREAT_CIRCLE);
              var terrainDistance = lengthMeasurer.getLength(pathPositions, true, WorldWind.GREAT_CIRCLE);
              var geographicDistance = lengthMeasurer.getGeographicDistance(pathPositions, WorldWind.GREAT_CIRCLE);
              var area = areaMeasurer.getArea(pathPositions, false);
              var terrainArea = areaMeasurer.getArea(pathPositions, true);
  
              // Display the results.
              geoDistSpan.textContent = (geographicDistance / 1e3).toFixed(3);
              distSpan.textContent = (distance / 1e3).toFixed(3);
              terrainDistSpan.textContent = (terrainDistance / 1e3).toFixed(3);
              projectedAreaSpan.textContent = (area / 1e6).toFixed(3);
              terrainAreaSpan.textContent = (terrainArea / 1e6).toFixed(3);
          }
docs: Calculate the length and area measurements of the path defined before.