12)
Which is equivalent to (0.25 -0.3) - (0.8 -0.25)
-0.55 +0.55
-0.55-0.05
0.55 +0.55
0 0.55-0.05

-0.55-0.05

Step-by-step explanation:

When you solve (0.25-0.3)-(0.8-0.25), you get -0.6. -0.55-0.05= -0.6

< 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⭐