Englishfor English speakers
operating
—
adjective
involved in a kind of operation
the operating conditions of the oxidation pond
—
adjective
(= operational, in operation)
being in effect or operation
de facto apartheid is still operational even in the 'new' African nations
— Leslie Marmon Silko
bus service is in operation during the emergency
the company had several operating divisions
radius
Noun
—
A radius is a straight line between the centre of a circle and its circumference.
To find the area of a circle, you have to know the length of the radius.