The reason for this is that the shape of the letter delta resembles the triangular shape of a river delta.
Here's why:
* River Deltas: River deltas are landforms created at the mouth of a river where it flows into a larger body of water (like a lake or sea). They have a triangular shape, with the river branching out like a fan.
* Delta Symbol: The Greek letter Δ is also triangular in shape. This resemblance was likely noticed by ancient Greeks who used both the letter and the geographic feature.
Therefore, the delta shape is named after the Greek letter delta due to their shared triangular form.