Rail diamond geometry: The side length of a rail diamond (formed by two tracks crossing) can be obtained by dividing the gauge of the track by which trigonometric function of the acute crossing angle?
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ASine of the acute crossing angle
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BCosine of the acute crossing angle
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CTangent of the acute crossing angle
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DCotangent of the acute crossing angle
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ESecant of the acute crossing angle
Answer
Correct Answer: Sine of the acute crossing angle
Explanation
Introduction / Context:A rail diamond is a rhombus-like assembly where two tracks intersect. Knowing how to compute its side from gauge and crossing angle is fundamental to detailing and setting out.
Given Data / Assumptions:
- Gauge G is the perpendicular spacing between track centerlines (or running faces) as appropriate.
- Acute crossing angle θ is the small angle between the two track centerlines.
- Side of the diamond is measured along one of its four equal edges.
Concept / Approach:Projecting the gauge onto the direction of the diamond side uses right-triangle relations. The component relationship leads to: side = G / sin θ for the typical geometric construction where the gauge spans the short diagonal direction and the side is inclined at angle θ.
Step-by-Step Solution:Let diamond side length be S and acute crossing angle be θ.By geometry, G corresponds to S * sin θ.Therefore, S = G / sin θ.
Verification / Alternative check:Check limiting behavior: as θ increases, sin θ increases and S decreases, which is consistent with a steeper crossing yielding a shorter side for the same gauge.
Why Other Options Are Wrong:
- Cosine / tangent / cotangent / secant do not match the standard projection relation used in diamond layout.
Common Pitfalls:Mixing up the roles of diagonal vs side; using cos instead of sin due to a misdrawn triangle.
Final Answer:Sine of the acute crossing angle