- Volume Calculator
- Area Calculator
- Perimeter Calculator
- Surface Area Calculator
- Circle Calculator
- Rectangle Calculator
- Triangle Calculator
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Tangent Line Length from External Point CalculatorFind the length of a tangent line drawn from an external point to a circle. Enter the distance to the center and the radius to get L = √(d² − r²).
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Circular Segment CalculatorCalculate the area, chord, arc length, height (sagitta), apothem and perimeter of a circular segment from a circle's radius and central angle.
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Circle CalculatorFree circle calculator: enter radius, diameter, circumference or area and instantly get the other three, plus results expressed in terms of pi.
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Pie Chart Angle CalculatorConvert a value and total into a pie chart slice angle in degrees. Calculate the exact wedge angle and percentage for any category instantly.
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Circle Area CalculatorCalculate the area of a circle quickly and accurately with this Circle Area Calculator. Simply input the radius to determine the precise area of any circular shape.
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Circumscribed Circle of a Rectangle CalculatorFind the circumscribed circle of a rectangle: enter side a and b to get the circumcircle radius, diameter, area, rectangle area and area ratio.
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Radius of a Circle CalculatorFind the radius of a circle from its diameter, circumference, or area. Free online calculator using r = C/(2π) = √(A/π) with instant results.
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Standard Equation of a Circle CalculatorFind the standard equation of a circle (x−h)²+(y−k)²=r² from center and radius. Also get diameter, circumference, area, and general form.
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Standard Form to General Form of a Circle CalculatorConvert a circle from standard form (x-h)²+(y-k)²=r² to general form x²+y²+Dx+Ey+F=0. Enter center and radius to get D, E, and F instantly.
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Square Footage of a Circle CalculatorFind the square footage (area in ft²) of a circle from its diameter or radius. Also shows circumference, square yards, and square meters.
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Square Inches of a Circle CalculatorCalculate the area of a circle in square inches from its radius or diameter using A = πr². Fast, accurate, and free circle area calculator.
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Quarter Circle CalculatorCalculate the area, arc length, and perimeter of a quarter circle from its radius. Free, instant quarter circle geometry calculator with worked example.
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Quarter Circle Area CalculatorCalculate the area of a quarter circle from its radius using A = πr²/4. Also returns the quarter arc length and full perimeter instantly.
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Quarter Circle Perimeter CalculatorCalculate the perimeter of a quarter circle from its radius using P = (πr/2) + 2r. Instant arc length and straight-edge breakdown.
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Perimeter of a Sector CalculatorCalculate the perimeter of a circular sector from its radius and central angle (degrees or radians). Uses P = 2r + rθ with the arc length.
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Circle Perimeter CalculatorEnter a circle's radius in cm, m, in, or ft to instantly get its perimeter (circumference) using P = 2πr. Fast, accurate, and classroom-ready.
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Inscribed Angle CalculatorCalculate the inscribed angle of a circle from its central angle. The inscribed angle equals half the central angle subtending the same arc.
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General to Standard Form of a Circle CalculatorConvert a circle equation from general form x²+y²+Dx+Ey+F=0 to standard form (x−h)²+(y−k)²=r². Find center and radius instantly.
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General Form of the Equation of a Circle CalculatorConvert a circle's center (h, k) and radius r into general form x² + y² + Dx + Ey + F = 0. Instantly find the D, E and F coefficients.
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Foci of an Ellipse CalculatorFind the foci of an ellipse from its semi-axes and center. Computes focal distance c, both focus coordinates, and eccentricity instantly.
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Equation of a Circle from Diameter EndpointsFind the standard equation of a circle from the two endpoints of its diameter. Computes center, radius, diameter and r² instantly with steps.
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Diameter to Radius CalculatorConvert a circle's diameter to its radius instantly. Enter any diameter and get the radius using the simple formula r = d/2.
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Circle Radius, Diameter and Circumference from AreaEnter a circle's area to instantly find its radius, diameter and circumference. Uses r = sqrt(S/pi). Free, accurate geometry calculator.
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Diameter of a Circle CalculatorFind the diameter of a circle from its radius, circumference, or area. Free calculator with formulas, worked examples, and instant radius, circumference and area.
