Yes….. as it is written on the title of the measurement area is one of the advantages of Google Earth Pro, and I like this feature. Not to be confused to multiply with the scale and it is accurate, provided accurate for determining the boundaries.
At the picture I took an example of how to measure the roof area of buildings on Google Earth Pro with Ruler.
Line used to determine the appropriate distance from the line created.
Path to determine the appropriate distance from the line created but on this tool can be used to calculate the distance of many related lines.
Polygon used to calculate the area of a square and not circular.
Circle used to calculate the area of a circular.
To perform such measurements on the image, click on the specified position ….. for example at the corner of the roof of the building. Try to be as accurate as possible so that results are accurate too.
Another thing that must be considered also is the unit used. In the image above ….. look at the area, visible only zeros Square Kilometers. That’s because of my mistake to use units of kilometers. …..was too large for the size of the building area.
Another example is to measure the extent of the oil refinery (circle area) is shown in the figure below.