Find the values of x and y and write vector B. xi+yj * 4i + 2j = -16
How do I find x and y?
Last edited by INeedOfHelp; November 12th 2012 at 12:18 PM.
Follow Math Help Forum on Facebook and Google+
Equate the dot product of A and B to -16, and to what should you equate the dot product of B and C?
Once you write these products, then you will two equations in x and y.
2yj2+4xi2 = -16
So far is that right, or no?
I would write:
Now, since and are perpendicular, to what will we equate their dot product?
<2,1> * <2,3> = (4)+(3) = 7
That's not right, is it?
No, that's not right...you are taking the dot product of one half of A and C...you want to use B and C, and set it equal to what?
Equal to 0 because they are orthogonal vectors??
Yes, exactly...good. So what equation results from this?
Great! Now, you have:
Solve this system to get and .
So would vector B = <-6,4> ?
Yes, great work!
Thank you so much! (:
View Tag Cloud