The provincial seal shows a triangular flag, a symbol of victory in war.
Taoist temples may fly square or triangular flags.
From the highest roof-top was flying a white triangular flag.
By the 18th century this began to be flown as a rectangular as opposed to triangular flag, but remained essentially unchanged.
This was a triangular red flag with an elongated white cross.
A cord with small triangular flags was strung across the entrance to the rest area.
When I see small, plastic triangular flags like these, I think of used cars.
One with a small triangular red-and-blue flag.
In addition, pennants were known to be flown, illustrated as a triangular flag containing the same five pointed star and crescent.
Rectangular as well as triangular flags were used.