Semicircle
Area and perimeter, with the formula worked through and a drawing to scale.
Result
- Area
- 39.2699 sq ft
- = 39.2699 sq ft · 3.6483 m²
- Perimeter
- 25.708 ft
- = 25.708 ft · 7.8358 m
- Curved edge
- 15.708 ft
The working
Area: A = π r² ÷ 2
Perimeter: P = π r + 2r
A = π × 5² ÷ 2 = 39.2699 P = π × 5 + 2 × 5 = 25.708
Values in feet; areas in sq ft.
About the semicircle
Half a circle — an arched window or a half-round patio. The perimeter is the curved half plus the straight diameter.
Every formula on this site is explained step by step in Learn: area and perimeter.
Other shapes
Square Rectangle Parallelogram Rhombus Trapezoid (trapezium) Kite Triangle — three sides Triangle — base and height Right triangle Isosceles triangle Equilateral triangle Triangle — two sides and the angle between Circle Quarter circle Sector (pie slice) Circular segment (arch) Ring (annulus) Ellipse (oval) Regular polygon (pentagon, hexagon, octagon…) L-shape Any polygon — by corner points