Question:
In figure 9.36, AC ⊥ CE and ∠A:∠B: ∠C = 3: 2: 1, find
Solution:
∠A: ∠B: ∠C = 3: 2: 1
Let the angles be 3x, 2x and x
⇒ 3x + 2x + x = 180° [Angle sum property]
⇒ 6x = 180°
⇒ x = 30° = ∠ACB
∴ ∠ECD = 180° − ∠ACB − 90° [Linear pair]
= 180° − 30° − 90°
= 60°
∴ ∠ECD = 60°