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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
- $(2): \quad$ 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.
- 1969: C.R.J. Clapham: Introduction to Abstract Algebra ... (previous) ... (next): Chapter $8$: Field Extensions: $\S 40$. Construction with Ruler and Compasses
- 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): compasses
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): compass (compasses)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): compass (compasses)
- 2008: Ian Stewart: Taming the Infinite ... (previous) ... (next): Chapter $2$: The Logic of Shape: Problems for the Greeks