Can someone explain this to me?

Step-by-step explanation:

a). By applying tangent rule in the triangle,

   tanθ =

   θ =

   θ = 36.87°

   Therefore, θ < 45°

b). By using cosine rule in this triangle,

   cosθ =

   cosθ =

    θ = 45°

c). By using tangent rule,

  tanθ =

  θ =

  θ = 75.96°

  θ > 45°

< 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⭐

12cm

the answer is d