This social norm explains that people feel the need to repay the actions others have done for them. For this reason, we expect others to react accordingly to positive or negative interactions.
Some studies reveal that the norm of reprocity is an essential component of a society's stability, as it enourages individuals to take part in social reponsibility.
The angular measurement is half the angle in the center, so we deduce the angle BAC equals half the angle in the center. Which mean BAC = 1/2 BOC => BAC = 52/2 = 26°.
