Question

In the given figure, AB || CD || EF. Then, the value of x is ____.

• A. 20
• B. 50
• C. 70
• D. 130

Answer 1

The correct option is A 20

EF || CD and CE is transversal.
∴ ∠ECD + ∠CEF = 180°
[Co-interior angles]

⇒ ∠ECD + 130° = 180°
⇒ ∠ECD = 50°

AB || CD and BC is transversal.
∴ ∠ABC = ∠BCD
[Alternate interior angles]

⇒ 70° = x° + 50°
[∠BCD = ∠BCE + ∠ECD, ∠ECD = 50°]

⇒ x° = 20°
Hence, x = 20.