Radius bar (Mach.), a bar pivoted at one end, about which it swings,
and having its other end attached to a piece which it causes to move in
a circular arc. -- Radius of curvature. See under Curvature.
||Ra"di*us vec"tor (vk"tr). 1. (Math.) A straight line (or the length
||of such line) connecting any point, as of a curve, with a fixed
||point, or pole, round which the straight line turns, and to which it
||serves to refer the successive points of a curve, in a system of
||polar coördinates. See Coördinate, n.
2. (Astron.) An ideal straight line joining the center of an attracting
body with that of a body describing an orbit around it, as a line
joining the sun and a planet or comet, or a planet and its satellite.
Ra"dix (r"dks), n.; pl. L. Radices (rd"*sz), E. Radixes (r"dks*z). [L.
radix, -icis, root. See Radish.] 1. (Philol.) A primitive word, from
which spring other words; a radical; a root; an etymon.
2. (Math.) (a) A number or quantity which is arbitrarily made the
fundamental number of any system; a base. Thus, 10 is the radix, or
base, of the common system of logarithms, and also of the decimal
system of numeration. (b) (Alg.) A finite expression, from which a
series is derived. [R.] Hutton.