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Perpendicular
Two lines, vectors, planes, etc., are said to be perpendicular if they meet at a right angle. In 
, two vectors 
and 
are perpendicular
if their dot product
 |
(1)
|
In 
, a line with slope 
is perpendicular to a line
with slope 
. Perpendicular
objects are sometimes said to be "orthogonal."
In the above figure, the line segment 
is perpendicular
to the line segment 
. This relationship
is commonly denoted with a small square at the vertex
where perpendicular objects meet, as shown above, and is denoted 
.
Two trilinear lines
 |  |  |
(2)
|
 |  |  |
(3)
|
are perpendicular if
 |
(4)
|
(Kimberling 1998, p. 29).
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vector field
