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

  • Thread starter mr_coffee
  • Start date
  • #1
1,629
1
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.
 

Answers and Replies

  • #2
Integral
Staff Emeritus
Science Advisor
Gold Member
7,198
55
Call the vector you are given A, you need to find, and descripe the family of vectors (b) which satisfy the condition:

[tex] A \cdot b = 0 [/tex]
 
  • #3
1,629
1
thanks for the responce!
how do you find a family of vectors?
 
  • #4
TD
Homework Helper
1,022
0
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)
 
  • #5
1,629
1
Awesome! thanks again TD, you should be getting paid for this hah. :tongue:
 
  • #6
TD
Homework Helper
1,022
0
You're welcome :smile:
 

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