Two lines AB and CD are parallel. Let PQ be the transversal intersecting AB at M and CD at N. If ∠MND = 47º find ∠AMN.
- AOption (a)
107º
- BOption (b)
133º
- COption (c)
73º
- DOption (d)
47º
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Correct answer
47º
Why this answer is correct
Shortcut Trick
Parallel lines ⇒ alternate interior angles equal
⇒ ∠MND = ∠AMN
⇒ Given ∠MND = 47°
⇒ ∠AMN = 47°
∴ Answer = 47°
Alternate Method
Given:
AB ∥ CD
PQ is a transversal
∠MND = 47°
Formula:
Alternate interior angles are equal when lines are parallel
Calculation:
⇒ ∠MND and ∠AMN are alternate interior angles
⇒ ∠AMN = ∠MND
⇒ ∠AMN = 47°
∴ Final Answer = 47°
Additional Information
Alternate Interior Angles: Equal when a transversal cuts parallel lines
Corresponding Angles: Same relative position ⇒ equal
Co-interior Angles: Sum = 180° on same side
Key Tip: Always locate angle position before applying rule