The us postal service handles 17 pieces of mail each year. this is 40% of the world's total. how many pieces of mail are sent each year

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐

this is a good question! i'll do some research and come back when i have the answer!