Mathematics often is used to describe
relationship between two quantities.
To do this relational operators are
used in a mathematical expression.
A < B (“A less than B”)
X Y (“X greater than or equal to Y”)
V r3 (“V proportional to radius cubed”)
See Table 6.2 of Foundations text for
other relational operators.
The operator is used to indicated
proportionality between quantities.
(circumference of circle directly proportional to its
C = 2r
2 is the proportionality constant
(area of circle directly proportional to its radius
A = r2
is the proportionality constant
In the previous example, both the
circumference, C, and the area, A, were
directly proportional to the variable.
Other proportions are possible
Example: y 1
y is the inverse proportion of x squared.
Other Relational Notations
A right triangle with a base dimension, b, and
height, h. Area, A, can be expressed as:
A = f (b,h)
“The area A, is a function of the base, b, and
the height, h.”