BC ONLYIf a point P moves along a curve defined parametrically by P(t) = (x(t), y(t)),
where t represents time, then the vector from the origin to P is called the position
vector, with x as its horizontal component and y as its vertical component. The
set of position vectors for all values of t in the domain common to x(t) and y(t) is
called vector function.
A vector may be symbolized either by a boldface letter (R) or an italic letter
with an arrow written over it ( ). The position vector, then, may be written as
(t) = x, y or as R = x, y. In print the boldface notation is clearer, and will be
used in this book; when writing by hand, the arrow notation is simpler.