That triangular area is called a delta. It's named after a triangular shaped letter of the Greek alphabet.Note: A river that empties into a lake is most often known as the headwaters if it is the primary water source for body of water= or = tributary.
A lanteen sail
"triangular" is an adjective, not a noun. So there is no object such as "the triangular". The triangular WHAT?
Discharge
Carthage in North Africa.
This area is commonly known as the Sinai Peninsula.
Triangular prism
mayans political organization
Another name for a lateen sail is a "triangular sail." This type of sail is characterized by its triangular shape and is rigged at an angle to the mast, allowing for better maneuverability, especially when sailing against the wind. Lateen sails were widely used in Mediterranean maritime trade and have influenced various sailing cultures around the world.
it is also called a triangular prism
Triangular prism
A triangular pyramid is called a Tetrahedron ■