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Matemáticas

Calculadora de círculo

Introduce el radio, el diámetro, la circunferencia o el área de un círculo y obtén al instante los otros tres valores, además de la longitud de arco y el área de un sector. Funciona en mm, cm, m, pulgadas o pies.

Calculadora

Introduce el valor que conoces. Para el área, el valor se expresa en unidades cuadradas.
Área
78,5398 cm²
Circunferencia = 2 × π × radio. Área = π × radio². Para un sector, longitud de arco = radio × ángulo y área del sector = ½ × radio² × ángulo (ángulo en radianes).
Radio
5 cm
Circunferencia
31,4159 cm
Diámetro
10 cm
Radio
5 cm

El mismo círculo en otras unidades

Área (mm²)
7853,9816 mm²
Área (m²)
0,0079 m²
Área (in²)
12,1737 in²
Área (ft²)
0,0845 ft²
Circunferencia (mm)
314,1593 mm
Circunferencia (m)
0,3142 m
Circunferencia (in)
12,3685 in
Circunferencia (ft)
1,0307 ft
Una herramienta de referencia y planificación: verifica las fechas, cifras y requisitos oficiales importantes antes de fiarte de ellos.

Acerca de esta calculadora

A circle is fully described by a single measurement: give it the radius, the diameter, the circumference (the distance around) or the area, and the other three are fixed. This calculator takes whichever one you know and solves the rest at once, in millimetres, centimetres, metres, inches or feet. Switch to sector mode to slice the circle by a central angle and get the arc length, the area of the slice and the straight-line chord across it.

Cómo leer tus resultados

The large figure is the area; beside it sit the radius, diameter and circumference, all in the unit you chose. The “same circle in other units” panel restates the area and circumference in every other length unit, so a radius typed in inches can be read off in centimetres without retyping. In sector mode, arc length is the curved edge of the slice, sector area is the pie-piece area, and the chord is the straight line joining the two ends of the arc.

Cómo se calcula

From the radius r: diameter = 2r, circumference C = 2πr (= πd), area A = πr². Working backwards, a known circumference gives r = C ÷ (2π) and a known area gives r = √(A ÷ π). For a sector with central angle θ measured in radians, arc length = rθ, sector area = ½r²θ, and the chord = 2r·sin(θ ÷ 2); an angle entered in degrees is converted with θ = degrees × π ÷ 180.

Ejemplo práctico

A radius of 5 cm.

The diameter is 10 cm, the circumference is about 31.42 cm (2 × π × 5), and the area is about 78.54 cm² (π × 5²). A 90° sector of that circle has an arc 7.85 cm long and an area of 19.63 cm².

Preguntas frecuentes

How do I find circumference from the radius or diameter?

Circumference is 2 × π × radius, which is the same as π × diameter. With a radius of 5 cm that is 2 × 3.14159 × 5 ≈ 31.42 cm. Enter the radius (or diameter) and the calculator returns the circumference instantly.

Can I work backwards from the circumference or area?

Yes. Choose “Circumference” or “Area” as the value you know. The calculator inverts the formulas — radius = circumference ÷ (2π), or radius = √(area ÷ π) — and then fills in every other property of the circle.

What is the arc length and area of a sector?

A sector is a pie-slice bounded by two radii and an arc. For a central angle θ in radians, the arc length is r × θ and the sector area is ½ × r² × θ. A full turn (360° or 2π) gives back the whole circumference and area; a 90° sector is exactly one quarter of each.

Which units can I use?

Millimetres, centimetres, metres, inches and feet. Lengths convert through the exact international definitions (1 inch = 2.54 cm, 1 foot = 0.3048 m), and areas convert by the square of the length factor, so 1 ft² = 0.0929 m².

Fuentes

Revisado por el equipo de YouCalc · Última revisión

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