What is the curved rectangular wedge in a dome called?

How does gianlorenzo bernini's fountain of the four rivers reflect the beliefs of the people during the baroque period of italy? the fountain emphasized the ongoing conflict between artist and patron during the baroque period. the fountain served as a public emblem of the catholic church's dominance and authority. the fountain symbolized the importance of the protestant church as an art patron in italy. the fountain reflected the belief in the complete control of italian royalty over the italian citizens. 1 points save answer question 3 what is a baroque convention bernini used in his david?