Allegedly, the lateen sail design made it possible to sail closer into the wind. That is, less than 45 degrees from the direction the wind is blowing. No sail boat can sail directly into the wind. Yet.
Lateen
It is called the lateen sail.
A three sided sail is known as a Lateen sail or also a triangular sail. With a four sided sail one is only able to sail against the wind, but with a Lateen sail it is possible to sail more directly into the wind.
Trapezoidal, actually. But the square sails were called square sails. Lateen or square could be referred to as yards.
They were referred to as "four-cornered" sails.
The triangular sail was invented beginning in the 16th century. They were first seen in the Mediterranean as single yarded lateen sails.
One type is the "lateen sail", but there are also jibs; Genoa & spinnaker.
The triangular lateen sail dominated the Mediterranean in the Middle Ages. The earliest evidence of it is in the 1st century BCE on a wall painting in Alexandria.
I'm not an expert, but I believe you can sail closer to the wind with a lateen-rigged sail than with square sails.
a Lateen Sail
Triangular-shaped sails helped catch wind from the sides and rear.
A lateen sail. Was/is able to be moved left or right. It made/makes ships easier to turn.