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I have two (two dimentional) linear equations (in the plane). and i am required to find out the angle between them. I have found the solution somewhere.

the solution uses two vectors orthogal to the two lines.

The problem now i have is: How to determine those orthogonal vectors?

e.g: two equations are: 3x + y = 5 and 2x - y =4

Now the solution goes like this:

n1 = 3i + j and n2 = 2i - j.

Then the angle between them is found out by using Dot product. This is the required angle.

How did they determine n1 and n2?

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# Homework Help: How to find a vector orthogonal to a line

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