# Definition:Compass

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## Contents

## Definition

A **compass** is an ideal tool for drawing circles.

Hence it can be used according to Euclid's third postulate to construct a circle using any two given points:

- $(1): \quad$ the center

and:

- $(2): \quad$ an arbitrary point on the circumference.

## Also known as

A **compass** should strictly be called a **pair of compasses** (using the same idea as a **pair of scissors**), but this is considered pedantic.

Note, however, that **compass** is also the word for a navigational aid based upon the north-pointing property of a magnetized needle. If there exists any risk of confusion, then **pair of compasses** is preferred.

## Also see

## Sources

- 1969: C.R.J. Clapham:
*Introduction to Abstract Algebra*... (previous) ... (next): Chapter $8$: Field Extensions: $\S 40$. Construction with Ruler and Compasses - 2008: David Nelson:
*The Penguin Dictionary of Mathematics*(4th ed.) ... (previous) ... (next): Entry:**compass (compasses)** - 2008: Ian Stewart:
*Taming the Infinite*... (previous) ... (next): Chapter $2$: The Logic of Shape: Problems for the Greeks