About how long would it take for one of the footprints left by the apollo astronauts to be erased? (hints: use the moon's surface area to determine the impact rate per square centimeter, and estimate the size of a footprint.)

time take for one of the footprints left to be erased is ( 1.21 * 10^9 ) degree

< 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⭐