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Circular Segment Area Calculator

A circular segment is a region of a circle cut off from the rest of the circle by a chord. It's the area between the chord and the arc. Use this calculator to find the area of such a segment by providing the circle's radius and the central angle subtended by the arc.

Enter the radius of the circle (e.g., 10)

Enter the central angle in degrees (e.g., 60)

How it works

A circular segment is a region of a circle cut off from the rest of the circle by a chord. It's the area between the chord and the arc. Use this calculator to find the area of such a segment by providing the circle's radius and the central angle subtended by the arc.


The Formula
The area of a circular segment is calculated using the formula:
Area = r² * (θ - sin(θ)) / 2
Where:
'r' is the radius of the circle. 'θ' (theta) is the central angle in radians.

Worked Example
  1. Example: Finding the Area of a Segment

    Imagine a circle with a radius of 10 cm. If a chord cuts off a segment with a central angle of 60 degrees, what is the area of that segment? First, convert 60 degrees to radians: 60 * (π / 180) = π/3 radians. Then, apply the formula: Area = 10² * (π/3 - sin(π/3)) / 2 Area = 100 * (1.0472 - 0.8660) / 2 Area = 100 * (0.1812) / 2 Area = 9.06 cm² Our calculator will do this for you in seconds!


Tips, Assumptions & Limitations
  • Ensure your radius is a positive value.
  • The central angle should be between 0 and 360 degrees, inclusive.
  • The calculator automatically converts degrees to radians for the formula.
FAQ

A circular segment is the area of a circle that is 'cut off' from the rest of the circle by a chord. It's the region bounded by the chord and the arc it subtends. Think of it as a slice of pizza (a sector) with the triangle part removed.

A circular sector is a region bounded by two radii and the arc between them, like a slice of pizza. A circular segment, on the other hand, is the region bounded by a chord and the arc it subtends. You can find the area of a segment by subtracting the area of the triangle formed by the two radii and the chord from the area of the corresponding sector.

The standard formula for the area of a circular segment, Area = r² * (θ - sin(θ)) / 2, requires the angle θ to be in radians for the 'θ - sin(θ)' part to work correctly. If you use degrees directly, the result will be incorrect. Our calculator handles the conversion for you, so you can input degrees directly.

Companion article

Circular Segment Area Calculator: Find the Area of a Circular Segment

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