Semicircle Area Calculator

Area and perimeter of a semicircle.

Area 39.27

Perimeter 25.708

Formula: area = ½ π r² ; perimeter = πr + 2r

Step-by-step with your numbers:

1. Values used:

2. Radius = 5

4. Area = 39.27

5. Perimeter = 25.708

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Half-circle measurements.

The math behind it

Area = ½ × π × r². Perimeter = the curved πr plus the straight diameter 2r.

Radius 5 → area 39.27.

Perimeter includes the flat side?

Yes — the diameter is part of a semicircle's boundary.