Radius (geometry)
Radius is the distance from the center of a circle to the outside edge.

The relationship between the radius and the circumference of a circle is .

Starships often scanned within a given radius when making an analysis or evaluation of nearby space.

In the alternate timeline created by the Na'kuhl, Nazis searched for Captain Archer within a fifteen-mile radius. ()

While attempting to assassinate Gul Dukat, the Bajoran resistance gave Major Kira Nerys (as Luma Rahl) a Bajoran earring made of ultritium resin which, when detonated, had a blast radius of twenty meters. ()

After failing to obtain a transporter lock on the away team on Trelane's Gothos, Spock beamed aboard all lifeforms within a predetermined radius. ()

The 22nd century Vulcan hand scanner was capable of scanning within a three kilometer radius. ()

In the mirror universe, Doctor  measured the bite radius of a bite mark left behind by an unknown reptilian and determined it was likely at least two meters in length. ()

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Mathematics
Measurements