Why are angiosperms so called? In which structures do the seeds develop? Why are cotyledons considered an important part of seed?

(N/A) Angiosperms are so called because they produce seeds that are enclosed within a fruit,which develops from the ovary.
Seeds develop within the ovary,which matures into a fruit after fertilization.
Cotyledons are considered an important part of the seed because they are embryonic leaves. They often serve as a food storage organ for the developing embryo and,in many cases,emerge and become green to perform photosynthesis when the seed germinates.