Rename 1\10 and 1\4 using the least common denominator.

1/20

Step-by-step explanation:

10 x 2 = 20

4 x 5 = 20

the both have 20 and it's the first they have in common so that's the common denominator

< 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⭐