Shortcut → 3
Use the polygon tool to measure area and perimeter of the relevant items on the drawing.
Choose the polygon icon on the toolbar.
To start drawing a polygon, click on the relevant starting point, then select the necessary number of its other points by clicking on them.
To undo the last segment, press "Esc" or "Ctrl"/"Cmd" + "Z" or "Backspace".
To finish the polygon, click on the initial point or press the "Enter" button or use the right-click and choose the "Finish" option.