Length of Chord Calculator

Enter circle values from several measurement paths fast. Get chord length with supporting geometry details. Download results for homework, lab notes, and reports today.

Calculator Input

Formula Used

Radius and angle: L = 2r sin(θ / 2)

Diameter and angle: L = d sin(θ / 2)

Radius and center distance: L = 2 sqrt(r² - a²)

Radius and sagitta: L = 2 sqrt(2rs - s²)

Radius and arc length: θ = arc / r, then L = 2r sin(θ / 2)

Radius and sector area: θ = 2A / r², then L = 2r sin(θ / 2)

How to Use This Calculator

  1. Select the measurement method that matches your known values.
  2. Enter the required radius, angle, distance, sagitta, arc, or area.
  3. Choose degrees or radians when using an angle.
  4. Enter a unit label and decimal precision.
  5. Press Calculate to view the result below the header.
  6. Use CSV or PDF buttons to save the same calculation.

Example Data Table

Method Input Values Formula Chord Length
Radius and angle r = 10 cm, θ = 60 degrees L = 2r sin(θ / 2) 10 cm
Radius and distance r = 13 cm, a = 5 cm L = 2 sqrt(r² - a²) 24 cm
Radius and sagitta r = 8 cm, s = 2 cm L = 2 sqrt(2rs - s²) 10.583 cm
Radius and arc r = 12 cm, arc = 9 cm θ = arc / r 8.766 cm

Physics View of Chord Length

A chord is a straight line segment joining two points on a circle. In physics, this simple length appears in wave fronts, pulley motion, optics, circular tracks, orbit sketches, and sensor coverage. The value depends on the circle size and the position of the two endpoints. A larger radius usually creates a longer chord for the same central angle. A larger angle also opens the chord and increases its span.

Why Several Inputs Matter

Real measurements rarely arrive in one perfect format. A lab problem may give radius and central angle. A surveying sketch may give the distance from the center to the chord. An optics problem may describe sagitta, which is the height between the arc and the chord. This calculator accepts those common paths and converts them to one chord result. That makes checking work faster and reduces repeated hand calculations.

Interpreting the Result

The chord length is not the same as arc length. Arc length follows the curve. Chord length cuts straight across the circle. The difference grows as the central angle grows. For very small angles, both values can look close. For wide angles, the arc becomes clearly longer. The calculator also reports derived values when possible. These values help you verify whether the geometry is realistic.

Accuracy and Limits

Every formula assumes a true circle and consistent units. Radius, sagitta, arc length, distance, and diameter must share the same length unit. Angles can be entered in degrees or radians. Distance from the center cannot be greater than the radius. Sagitta cannot be negative or larger than the diameter. When an entry breaks these rules, the calculator shows a clear validation message.

Practical Uses

Use this tool for physics homework, circular motion examples, engineering sketches, and classroom demonstrations. It is also useful when comparing theoretical geometry with measured parts. Export the result when you need a record. The CSV file works well for spreadsheets. The PDF report is useful for notes, assignments, or quick documentation. Always round only after the final result. For teaching, it also shows how changing one input affects the final span. Try nearby values to build intuition before solving larger circular models in class or practice sets.

FAQs

What is a chord in physics geometry?

A chord is a straight segment connecting two points on a circle. It is useful in circular motion, optics, waves, and measurement sketches.

Is chord length the same as arc length?

No. Chord length is straight. Arc length follows the curved boundary. Arc length is usually longer for the same endpoints.

Which input method should I choose?

Choose the method matching your known data. Use radius and angle when given. Use sagitta, distance, arc, or area when those are provided.

Can I enter angles in radians?

Yes. Select radians in the angle unit field. The calculator also reports the derived central angle in degrees and radians.

Why must the center distance be less than radius?

The perpendicular distance from the center to a chord cannot exceed the radius. If it does, the chord cannot exist on that circle.

What is sagitta?

Sagitta is the height from the chord midpoint to the arc. It helps calculate chord length when the arc bulge is measured.

Can I download the result?

Yes. Use the CSV button for spreadsheet records. Use the PDF button for a simple printable report.

Does the calculator require one unit type?

Yes. Keep radius, diameter, sagitta, distance, and arc length in the same unit. Mixed units will produce incorrect results.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.