To fillet the leftmost corner, select the elements as indicated on the picture below by A and B. Then, you must select and left-click precisely on the arc element you want to keep. This is the pink arc on the picture below.
Select the other two corners A+B and A+C as shown at the picture below. Then select the correct arcs to keep. At the end of the operation the drawing should look something like the picture below.
You might want to zoom in on the area we will be working on, as on the picture below. |
Now the drawing is finished, and it should look like the one below: