Union: Trace the Outer Outline
When two shapes are combined (union, +, OR), the result is the OUTER outline of the merged area.
Tip: Trace around the outside of both shapes — that's your answer.
Intersection: Just the Overlap
When two shapes are intersected (AND), the result is JUST the overlapping region — the part both shapes share.
Tip: Ignore the parts that belong to only one shape.
Subtraction: Remove the Second Shape
When one shape is subtracted from another, the result is the first shape with the overlap removed.
Tip: The second shape acts like a cookie cutter — punch it out.
Watch the Order for Subtraction
Subtraction is NOT symmetric: A minus B is different from B minus A.
Tip: Check carefully which shape is being subtracted from which.