Question

Calculate:

 (ii) ∠ABC

Answer 1

Given: ACE = 130⁰; AD = BD = CD

Proof:

(ii)

∠ACD = ∠ABD + ∠DAB   [ Exterior angle is equal to sum of opp. interor angle ] 

But AD =BD
∴ ∠DAB = ∠ABD
⇒ 80⁰ = ∠ABD + ∠ABD
⇒ 2∠BD = 80⁰ 
⇒ ∠ABD = 40⁰ = ∠DAB.........(ii)