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# semicircle

noun (a semicircle, semicircles)

«semicircle» in the English dictionary: everyday — its meanings, how the lessons use it, and examples, each with its tree on Mova.

## Everyday

1. Half a circle: a shape made by cutting a circle in half along its diameter. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#m1)
2. Things arranged in a curved line like half a circle: «sit in a semicircle». [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#m2)

### In the lessons

Maths: a semicircle has a curved edge (half the circumference) and a straight edge (the diameter). Its area is half the circle's area: ½ × π × r². Its perimeter is half the circumference plus the diameter: πr + 2r. In class: «Sit in a semicircle on the carpet.» A protractor is a semicircle marked from 0° to 180°. In Alice, the animals sit in a ring for the Caucus-race.

### Examples

- Draw a semicircle with a compass. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x1)
- The children sat in a semicircle around the teacher. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x2)
- A protractor is shaped like a semicircle. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x3)
- The area of a semicircle is half the area of the full circle. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x4)
- A rainbow looks like a semicircle in the sky. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x5)
- If the radius is 2 cm, the semicircle's curved edge is about 6.28 cm. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/#x6)

### Note

«Semi-» means half. Countable. Maths trap: the perimeter is not just half the circumference – you must add the diameter.

## On Mova

- [Trees and pragmatics of «semicircle» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/semicircle/): every meaning and example parsed by Mova, with its dependency tree and frames.
- [«semicircle» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/semicircle.html) on Mova free.