Formulas
- Area: A = π·a·b
- Perimeter (Ramanujan): P ≈ π[3(a + b) − √((3a + b)(a + 3b))]
- Eccentricity: e = √(1 − b²/a²) (assuming a ≥ b)
- Focal distance: c = √(a² − b²)
- Semi-latus rectum: ℓ = b²/a
Ellipse calculator
For an ellipse with semi-major axis a and semi-minor axis b, the area is exact and the perimeter is approximated by Ramanujan's second formula (accurate to ~10⁻⁵ for moderate eccentricities).
Area
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Perimeter (Ramanujan)
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Eccentricity (e)
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Focal distance (c)
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Aspect ratio (a / b)
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Semi-latus rectum (ℓ)
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