The angle
between two vectors u and v is given by the equation![]()
Example: Find the angle between the vectors
and![]()
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We can use the same formula to find the angle between vectors in two, three or more dimensions:
Example: Find the angle between the vectors
and![]()
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To find the angle between two lines we use the same formula. The vectors
and
are the tangent vectors, which are easily identifiable since the general equation of a line is given by the equation
where
is a point on the line and
is the tangent vector.
Example: Find the angle between the lines
and![]()
Take
and![]()
![]()
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If the equation of the line is in column vector form, the process is almost identical:

then
![]()
![]()
The required angle is 180-56.51=123.49 degrees.