Find the angle between the lines
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We have lines,
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We need to find the angle between the lines.
The line 
 is parallel to vector 
.
Let 
. Then, we can say that
The line 
 is parallel to vector 
.
Similarly, let 
. Then, we can say that
The line 
 is parallel to vector 
.
If θ is the angle between the lines, then cosine θ is given by

Substituting values of 
 and 
 in the above equation, we get

Here,
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 …(i)
Also,
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 …(ii)
Substituting equation (i) and (ii) in cos θ, we get
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Thus, the angle between the lines is 
.