HELP PLS TIMED TEST How do rivers become larger as they travel across land?

Groundwater rises, adding water to rivers.
Tributaries combine, adding water to rivers.
Ice sheets melt slowly, adding water to rivers.
Rainfall in an area increases, adding water to rivers.

You have 2 sides that are 2 cms and you have 6 sides that are 1/2 cm and you have 4 sides that are 1 cm. the smallest sides are 1/2 the medium sized sides are 1 and the smallest are 1/2. so to find the perimeter you have to add them all up together so your answer will be 11 cm's