Difficulty: Easy
Correct Answer: 12 m
Explanation:
Introduction / Context:
When a straight wire spans between unequal heights, its inclination with the horizontal lets us relate the vertical difference to the wire’s length via basic trigonometry. The scenario forms a right triangle whose “opposite” is the height difference and whose hypotenuse is the wire.
Given Data / Assumptions:
Concept / Approach:
Let L be the wire length. Vertical rise between ends is Δh = 20 − 14 = 6 m. With angle θ to the horizontal, sin θ = (vertical rise)/L = Δh/L. Hence L = Δh / sin θ.
Step-by-Step Solution:
Verification / Alternative check:
Using components: vertical = L * sin 30° = L/2. Set L/2 = 6 ⇒ L = 12, consistent.
Why Other Options Are Wrong:
10 m and 8 m correspond to sin values inconsistent with 30° for a 6 m rise.
Common Pitfalls:
Accidentally using tan instead of sin (tan ties vertical to horizontal span, not to hypotenuse), or mixing which pole is taller.
Final Answer:
12 m
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