Dot product, i don't see what they want from me

AI Thread Summary
The discussion centers on understanding how to find a family of vectors that are perpendicular to a given vector in R^3, specifically the vector (-5, -6, -3). The key point is that the dot product of two vectors equals zero when they are perpendicular. To find the family of vectors, one can set up a general vector (x, y, z) and use the equation (-5)x + (-6)y + (-3)z = 0. This results in one equation with three variables, leading to infinite solutions by assigning values to two variables and solving for the third. The conversation highlights the method of using parameters to express these solutions.
mr_coffee
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hello everyone, i understand the dot product and its properties but i don't get what they want! They say...
The dot product of two vectors are perpendicular if a.b = 0.
Then any vector in R^3 perpendicular to

-5
-6
-3

note: that is a matrix above.

can be written in the form:
and it looks like parameteric forum they want, because they want a column of s and a column of t. but i don't see where I'm suppose to find more numbers.
 
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Call the vector you are given A, you need to find, and descripe the family of vectors (b) which satisfy the condition:

A \cdot b = 0
 
thanks for the responce!
how do you find a family of vectors?
 
First, take anoter "general" vectors, let's say (x,y,z). Take the dot product with (-5,-6,-3) and let it equal 0.
Now you have 1 equation with 3 variables which has infinite many solutions. Solve it by choosing two variables (e.g. let x = s and y = t, then solve for z)
 
Awesome! thanks again TD, you should be getting paid for this hah. :-p
 
You're welcome :smile:
 
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