Chord Analysis Calculator






Chord Analysis Calculator – Geometry & Circle Segment Tools


Chord Analysis Calculator

Precise geometrical calculations for circle segments, arcs, and chord properties.


Distance from the center to the edge of the circle.
Please enter a valid positive radius.



Straight-line distance between two points on the circle.
Chord length cannot exceed 2x Radius.


Chord Length
12.00
Central Angle
73.74°
Sagitta (Height)
2.00
Arc Length
12.87
Segment Area
16.35

Chord Visualization

Diagram updates in real-time based on input variables.


Proportional Chord Ratios for Reference
Ratio (c/r) Central Angle (°) Sagitta Ratio (h/r) Arc Ratio (s/r)

What is a Chord Analysis Calculator?

A chord analysis calculator is a specialized geometric utility designed to compute the intricate relationships within a circle segment. Whether you are an engineer designing a bridge arch, a carpenter calculating the curve of a window, or a student solving trigonometry problems, this chord analysis calculator simplifies complex calculations. A chord is defined as a straight line segment whose endpoints both lie on a circular arc. Analyzing these segments involves understanding how the radius, chord length, sagitta, and central angle interact.

Common misconceptions include the idea that chord length and arc length are proportional in a linear fashion. In reality, as the angle increases, the arc length grows faster than the chord length. Using a professional chord analysis calculator helps eliminate these errors by applying precise trigonometric identities.

Chord Analysis Calculator Formula and Mathematical Explanation

The math behind a chord analysis calculator relies on the properties of isosceles triangles formed by the circle’s center and the chord’s endpoints. Here are the primary formulas used:

  • Chord Length (c): \( c = 2r \sin(\frac{\theta}{2}) \)
  • Sagitta/Height (h): \( h = r(1 – \cos(\frac{\theta}{2})) \)
  • Central Angle (θ): \( \theta = 2 \arcsin(\frac{c}{2r}) \)
  • Arc Length (s): \( s = r\theta \) (where θ is in radians)
  • Segment Area: \( A = \frac{r^2}{2}(\theta – \sin\theta) \)
Variable Meaning Unit Typical Range
r Radius Units (cm, m, in) > 0
c Chord Length Units 0 to 2r
h Sagitta (Height) Units 0 to r
θ Central Angle Degrees (°) 0 to 360°

Practical Examples (Real-World Use Cases)

Example 1: Architectural Arch Design

An architect is designing a curved entrance with a width of 12 feet (chord length) and a total radius of 10 feet. By inputting these values into the chord analysis calculator, the architect finds that the sagitta (the height of the arch) is exactly 2 feet. This calculation is crucial for ensuring the arch fits within the structural frame.

Example 2: Mechanical Engineering Gear Tooth

An engineer needs to determine the arc length of a gear segment. The radius of the gear is 50mm and the central angle of one tooth segment is 15 degrees. The chord analysis calculator reveals a chord length of 13.05mm and an arc length of 13.09mm. This precision ensures the gears mesh perfectly without mechanical interference.

How to Use This Chord Analysis Calculator

  1. Enter the Radius: Start by defining the size of the circle by entering the radius.
  2. Select Input Mode: Use the dropdown to choose which secondary value you already know (Chord Length, Sagitta, or Angle).
  3. Input the Known Value: Enter the measurement into the corresponding field.
  4. Review Results: The chord analysis calculator will instantly display the other four dimensions, the segment area, and a visual representation.
  5. Copy and Save: Use the “Copy Results” button to transfer your technical data to a report or blueprint.

Key Factors That Affect Chord Analysis Calculator Results

  • Measurement Precision: Even a 1% error in radius measurement can significantly skew the calculated sagitta in shallow curves.
  • Units of Measurement: Always ensure the radius and the second variable use the same units (e.g., both in millimeters).
  • Material Expansion: In engineering, heat can expand metals, changing the chord length. This chord analysis calculator assumes a rigid geometric state.
  • Angle Units: Most manual calculations fail because of confusion between degrees and radians. Our tool handles this conversion automatically.
  • Limit of the Chord: A chord cannot be longer than the diameter (2r). If you enter a value higher than this, the calculator will flag an error.
  • Segment Orientation: The chord analysis calculator calculates the “minor segment” (the smaller area) by default for angles under 180°.

Frequently Asked Questions (FAQ)

What is a chord in geometry?
A chord is a straight line joining two points on any curve, though it most commonly refers to points on a circle’s circumference.
How do I find the radius if I only have the chord and height?
You can use the formula \( r = \frac{h}{2} + \frac{c^2}{8h} \). Our chord analysis calculator can also work backward from these variables.
What is the sagitta?
The sagitta is the vertical distance from the center of the chord to the highest point of the arc. It is often simply called the “height” of the segment.
Does the calculator handle angles larger than 180 degrees?
Yes, the chord analysis calculator handles angles up to 360 degrees, representing major segments.
Can I use this for non-circular curves?
No, this specific chord analysis calculator is designed for circular geometry where the radius is constant.
Why is my segment area negative?
This usually happens if the input values are geometrically impossible (e.g., chord longer than diameter).
What is the difference between arc length and chord length?
Chord length is the straight distance “as the crow flies,” while arc length is the distance measured along the curved perimeter.
Is this tool useful for woodworking?
Absolutely. Woodworkers use the chord analysis calculator to determine the curve of table edges, arched door frames, and custom molding.

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