Question

In figure, ∠ABC = 69⁰ , ∠ACB = 31⁰ , find ∠BDC

Answer 1

In ∆ABC. ∠BAC + ∠ABC + ∠ACB = 180⁰ 

[Sum of all the angles of a triangle is 180⁰ ] 

 ⇒ ∠BAC + 69⁰ + 31⁰ = 180⁰ 

 ⇒ ∠BAC + 100⁰ = 180⁰ 

 ⇒ ∠BAC = 180⁰ - 100⁰ = 80⁰ 

 Now, ∠BDC = ∠BAC = 80⁰ .