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Math • Semicircle Area Calculator

Semicircle Area Calculator

Calculate the area and perimeter of a semicircle (half circle) from its radius.

Arc Length (L = rθ)
10.472
θ in radians = 1.0472
Sector Area (A = ½r²θ)
52.360
Semicircle Reference (θ = 180°, radius 10)
Area = ½πr²
157.080
Perimeter = πr + 2r
51.416
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Calculation Guide & Reference

Semicircle Area & Perimeter Mathematics

Semicircle area calculator computes the area and perimeter of a half circle from its radius.

Standardized Mathematical Formula
Area = (1/2)πr² | Perimeter = πr + 2r

A semicircle is exactly half a circle, cut along a diameter. Its area is half the full circle's area (πr²). Its perimeter combines the curved half-circumference (πr) with the straight diameter edge (2r) that closes the shape.

Variables:
r:Radius of the semicircle
How It Works (Step-by-Step)
  • 1Enter the radius (r) of the semicircle.
  • 2View the area and full perimeter (arc plus diameter edge).
Real-World Numerical Example
A Semicircle with Radius 10

A semicircular window has a radius of 10 units.

•Area: 0.5 × π × 10² ≈ 157.08 square units.
•Perimeter: (π × 10) + (2 × 10) ≈ 31.42 + 20 = 51.42 units.
Result: The semicircle has an area of about 157.08 square units and a perimeter of about 51.42 units.
Calculation Best Practices & Tips
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In statistical analysis, always check both the mean and median to identify if data distribution is skewed by outliers.
When calculating percentage changes, ensure you divide by the original starting baseline value: ((New - Old) / Old) * 100.

Frequently Asked Questions (FAQ)

Yes — the perimeter of a semicircular shape is the total distance around its boundary, which includes both the curved arc (πr) and the straight diameter edge (2r) that closes the shape.

A semicircle's area is always exactly half of a full circle with the same radius, since it's literally one half of that circle.

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