Bola Aberta

|x−c| < r.
Created by
Renato Passos, Eng. de Software
Reviewed by
Renato Passos, Eng. de Software

Last updated: Apr 18, 2026

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About this calculator

The Open Ball Calculator is a mathematical tool used to verify if a point belongs to an open ball in a metric space. An open ball is defined as the set of all points x that are at a distance less than r from a central point c. This is mathematically expressed as |x−c| < r, where |x−c| denotes the distance between x and c.

The formula used is based on the definition of an open ball in topology. For a given point c and a radius r, the calculator checks if the distance between the point of interest and the central point is less than the radius. This allows determining if the point is inside the open ball.

This calculator is useful in various applications in mathematics and science, such as in analyses of convergence of sequences, in set theory, and in topology. It helps to visualize and work with topological concepts in a more concrete way.

When using the calculator, it is essential to be careful with the units of measurement and ensure that the entered values are coherent. Additionally, it is crucial to understand the context in which the open ball is being applied, to correctly interpret the results.

Frequently asked questions

What is an open ball?

An open ball is the set of all points that are at a distance less than a certain radius from a central point.

How does the calculator work?

The calculator checks if the distance between the point of interest and the central point is less than the given radius.

What are the applications of an open ball?

The open ball has applications in convergence analysis, set theory, topology, and other areas of mathematics.

What precautions should I take when using the calculator?

Check the units of measurement and ensure that the entered values are coherent and appropriate for the context.

Can the calculator handle complex metric spaces?

Yes, the calculator can be used with different types of metric spaces, as long as the distance can be calculated meaningfully.

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