RIC-1069 Maths terms and tables

List of mathematical terms
R
Radian
The size of an angle at the centre of a
circle formed by two radii and an arc
that is the length of the radius. [Note
that 1 radian ≈ 57º.]
Radius
A line segment with one end point as
the centre of a circle and the other
end point on the circle. [The plural is
radii or radiuses. See p. 94].
e.g.
e.g.
r
radius
≈ 57º
r
radius
Random sample
A sample chosen from a population in such a way that all members have
an equal chance of being selected.
Range
In statistics, the difference between
the greatest and least values in a set of
data.
e.g.
In a set of scores where the
lowest is 40 and the highest is
90, the range is 50.
Rate
A comparison of two different
quantities.
e.g.
60 km/h
Ratio
The comparison of one number to
another by division [see pp. 70–71].
e.g.
The ratio of 3 to 4 can be
expressed as 3 / 4
or as 3:4
Rational number
Any number that can be expressed as
a fraction [see pp. 70–71].
Ray (Half-line)
Part of a line with one end point.
e.g.
3 = 3 / 1
3.7 = 37 / 10
2 1 / 4
= 9 / 4
e.g.
Real number
Any number that can be represented on the number line; i.e. all rational
numbers (such as 3 / 4
) and all irrational numbers (such as √2). [√–1 is an
example of an ‘unreal’ or imaginary number. See p. 71.]
Reciprocal (Inverse)
The product of a number and its
reciprocal is one.
e.g.
2
/ 3
is the reciprocal of 3 / 2
and
vice versa; and the reciprocal of
any number n is 1 / n
.
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