In the given figure, ∠ABD = 130° and ∠EAC = 120°. Prove that AB > AC.
∠ABD + ∠ABC = 180° | Linear Pair Axioms
⇒ 130° + ∠ABC = 180°
⇒ ∠ABC = 50° ...(1)
∠C AE + ∠C AB = 180° | Linear Pair Axiom
⇒ 120° + ∠CAB = 180°
⇒ ∠CAB = 60° ...(2)
In ∆ABC,
∠ABC + ∠BCA + ∠CAB = 180°
| Angle sum property of a triangle
⇒ 50° + ∠BCA + 60° = 180°
⇒ ∠BCA = 70° ...(3)
From (1) and (3),
∠BCA > ∠ABC
∴ AB > AC
| Side opposite to greater angle is longer